Publications | FX Lab at Stanford University

2024

Heterogeneous Cluster Energetics and Nonlinear Thermodynamic Response in Supercritical Fluids

Jingcun Fan, Nguyen Ly, and Matthias Ihme

Physical Review Letters, Dec 2024

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Direct observation of ultrafast cluster dynamics in supercritical carbon dioxide using X-ray Photon Correlation Spectroscopy

Arijit Majumdar, Haoyuan Li, Priyanka Muhunthan, Alexander Späh, Sanghoon Song, Yanwen Sun, Matthieu Chollet, Dimosthenis Sokaras, Diling Zhu, and Matthias Ihme

Nature Communications, Dec 2024

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Supercritical fluids exhibit distinct thermodynamic and transport properties, making them of particular interest for a wide range of scientific and engineering applications. These anomalous properties emerge from structural heterogeneities due to the formation of molecular clusters at conditions above the critical point. While the static behavior of these clusters and their effects on the thermodynamic response functions have been recognized, the relation between the ultrafast cluster dynamics and transport properties remains elusive. By measuring the intermediate scattering function in carbon dioxide at conditions near the critical point with X-ray photon correlation spectroscopy, we directly capture the cross-over dynamics between 4 and 13 picoseconds, revealing the transition between ballistic and diffusive motion. Complementary analysis using large-scale molecular dynamics simulations reveals that this behavior arises from collisions between unbound molecules and clusters. This study provides direct evidence of the ultrafast momentum exchange between clusters, which has significant impact on transport properties, solvation processes, and reaction kinetics in supercritical fluids.
An enrichment wall modeling framework for spectral element methods

Steven R Brill, Pinaki Pal, Muhsin Ameen, Chao Xu, and Matthias Ihme

Physics of Fluids, Dec 2024

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In the present work, a first-of-its-kind enrichment wall-model is developed within the spectral element method (SEM) framework for large-eddy simulations (LES) of wall-bounded turbulent flows. The method augments the polynomial solution in the wall-adjacent elements with an analytical law-of-the-wall enrichment function representing the mean velocity near the wall. In the solution representation, this enrichment function captures the large gradients in the boundary layer, which allows the polynomial modes to represent the turbulent fluctuations. The enriched solution is able to resolve the shear stress at the wall without any modification to the no-slip wall boundary conditions, which allows for greater accuracy in the near-wall region compared to traditional methods. The enrichment wall modeling approach is implemented in a high-order SEM computational fluid dynamics solver, Nek5000, and its performance is assessed in turbulent channel flow wall-modeled LES for a range of Reynolds numbers. It is demonstrated that the enrichment wall-model improves solution accuracy on under-resolved near-wall grids as compared to traditional shear stress wall-models.
Uncertainty quantification in coupled wildfire–atmosphere simulations at scale

Paul Schwerdtner, Frederick Law, Qing Wang, Cenk Gazen, Yi-Fan Chen, Matthias Ihme, and Benjamin Peherstorfer

PNAS Nexus, Dec 2024

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Uncertainties in wildfire simulations pose a major challenge for making decisions about fire management, mitigation, and evacuations. However, ensemble calculations to quantify uncertainties are prohibitively expensive with high-fidelity models that are needed to capture today’s ever-more intense and severe wildfires. This work shows that surrogate models trained on related data enable scaling multifidelity uncertainty quantification to high-fidelity wildfire simulations of unprecedented scale with billions of degrees of freedom. The key insight is that correlation is all that matters while bias is irrelevant for speeding up uncertainty quantification when surrogate models are combined with high-fidelity models in multifidelity approaches. This allows the surrogate models to be trained on abundantly available or cheaply generated related data samples that can be strongly biased as long as they are correlated to predictions of high-fidelity simulations. Numerical results with scenarios of the Tubbs 2017 wildfire demonstrate that surrogate models trained on related data make multifidelity uncertainty quantification in large-scale wildfire simulations practical by reducing the training time by several orders of magnitude from 3 months to under 3 h and predicting the burned area at least twice as accurately compared with using high-fidelity simulations alone for a fixed computational budget. More generally, the results suggest that leveraging related data can greatly extend the scope of surrogate modeling, potentially benefiting other fields that require uncertainty quantification in computationally expensive high-fidelity simulations.
On the importance of species immiscibility in mixing-layer dynamics at supercritical pressures

Nguyen Ly, and Matthias Ihme

International Journal of Multiphase Flow, Nov 2024

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The mixing dynamics of injected propellants is a key factor in determining the ignition performance and combustion-instability response of rocket engines, internal combustion engines, and gas turbines. A key source of uncertainty in the prediction of phase-exchange dynamics is the immiscibility of the injected propellants at supercritical pressure conditions, which induces liquid/vapor phase separation and surface-tension dynamics. While experimental observations indicate the presence of liquid/vapor interfacial structures, this interfacial dynamics is typically neglected in numerical analyses. To address this issue, the objective of the present study is to systematically evaluate the importance of species immiscibility on the phase-exchange dynamics of cryogenic LOX/GH2 mixing layers at typical rocket engine injection conditions. This is accomplished by comparing simulations of (i) a recently developed interface-capturing Regularized-Interface Method (RIM) formulation, and (ii) the commonly employed Diffuse-Interface Method (DIM) formulation. Analysis shows that the interfacial dynamics significantly impact the atomization and mixing of the propellants in the near-injector region, which is not captured by the DIM formulation. The findings of this study extend to other immiscible injection systems, such as LOX/kerosene and hydrocarbon-fuel/air, thereby highlighting the importance of resolving species immiscibility in simulating high-pressure combustion engines.
Stable supercritical interfaces do not exist without surface tension

Nguyen Ly, and Matthias Ihme

Nature Communications, Oct 2024

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A high-fidelity ensemble simulation framework for interrogating wildland-fire behaviour and benchmarking machine learning models

Qing Wang, Matthias Ihme, Cenk Gazen, Yi-Fan Chen, and John Anderson

International Journal of Wildland Fire, Nov 2024

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Turbulence in disguise: Reactive flows in porous media mimic turbulent behavior

Emeric Boigné, Sadaf Sobhani, Joseph C Ferguson, and Matthias Ihme

Physical Review Fluids, Oct 2024

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Chemical reactions in porous media play a pivotal role in various biological, environmental, and engineering applications, yet understanding flow-chemistry coupling within pores remains an outstanding challenge. This article examines a parallel between how chemical reaction fronts are impacted by (i) turbulence in unconfined flows, and (ii) hydrodynamic dispersion in porous media flows, even at laminar flow conditions. A regime diagram is constructed from which hitherto overlooked regime transitions are identified. The results are expected to improve our understanding of pore-scale coupling, with implications relevant to a broad range of applications.
Mechanisms and models of the turbulent boundary layers at transcritical conditions

Fangbo Li, Weiwei Zhang, and Matthias Ihme

Physical Review Fluids, Oct 2024

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Computational models for high-pressure transcritical turbulence in wall-modeled large-eddy simulations typically rely on wall-function models to overcome the need for resolving the boundary layer structures. However, the mechanisms and models of a turbulent boundary layer at transcritical conditions remain poorly understood since the near-wall flow and heat transfer are significantly affected by the enhanced fluctuations and steep gradients in thermodynamic properties. To address this issue, we study the mechanisms of transcritical turbulent boundary layers and wall-attached models at transcritical conditions. It is shown that the real-fluid variable-property effects are associated with the coupling between the near-wall cycle and the wall-normal coherent motions in the outer layer, resulting in the amplification of turbulent energy in the outer layer and noticeable energy transfer between the logarithmic layer and the outer layer; hence, turbulence in the logarithmic layer is modulated by the outer layer. Based on this underlying physical principle, we propose the characteristic velocity and length scales for the attached eddy at transcritical conditions, and extend the attached eddy model to transcritical turbulent boundary layers by introducing a mixed scaling that incorporates both inner and outer scalings. We show that the characteristic scales and extended attached eddy model perform well in characterizing the structures in transcritical turbulent boundary layers.
A regularized-interface method as a unified formulation for simulations of high-pressure multiphase flows

Nguyen Ly, and Matthias Ihme

Journal of Computational Physics, Dec 2024

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The injection of multi-species fluids into high-pressure and high-temperature environments beyond the species’ critical points is commonly found in engineering applications. At these conditions, for immiscible species, both subcritical interfacial dynamics and supercritical mixing can coexist due to variations in temperature around the mixture critical point. The modeling of these complex transcritical phenomena for large-scale configurations is so far not possible. To address this issue, we propose the Regularized-Interface Method (RIM) as a unified formulation that can describe both sub- and supercritical processes as well as the transition between them. The proposed method is derived via filtering of the nanoscale interface-resolving formulation based on van der Waals’ linear gradient theory. Thus, this approach allows for the consistent modeling of interfacial dynamics that vanishes at supercritical conditions, while significantly reducing the temporal and spatial resolution constraints of the original nanoscale formulation. The resulting RIM formulation is examined in interface-capturing simulations of sub-, trans-, and supercritical fuel injection processes, involving droplets and jets. These results highlight the importance of resolving spatio-temporal transitions from subcritical interfacial dynamics to supercritical mixing in high-pressure multiphase simulations, in contrast to commonly employed diffused-interface methods, where interfacial dynamics are often neglected.
Low Order Model for Generating Supersonic Cavity Combustion Ignition Probability Maps

Ryan Chen, Matthew Bonanni, and Matthias Ihme

In AIAA AVIATION FORUM AND ASCEND 2024, Jul 2024

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Ignition probability maps are useful for characterizing ignition mechanisms in supersonic combustion engines. However, evaluating the ignition probability in 3D scramjet geometries using high-fidelity ensemble simulations is computationally expensive. This work offers a cost-effective alternative by using low-order models to approximate results obtained from 3D large-eddy simulations (LES), with a focus on the RC19 scramjet geometry located at the Air Force Research Laboratory (AFRL). To accomplish this, a quasi-3D RC19 mesh geometry that assumes spanwise uniformity is used to generate a 2D probabilistic ignition map using LES. Validated through comparison with experimental and computational ignition maps of the RC19 scramjet cavity, this map is used as a baseline of comparison for low-order model approaches. Statistical quantities from an inert simulation of the quasi-3D scramjet cavity are then sampled to perform stochastic 0D perfectly stirred reactor (PSR) simulations and produce a low-order ignition map. Next, the 0D simulation is modified to incorporate the advection and mixing properties present in the flow, improving the prediction. The ignition maps for the quasi-3D geometry generated from LES and 0D PSR models are compared to assess the performance of the proposed modeling approaches. The 0D PSR and advecting 0D PSR maps produced mean absolute errors of 22.8% and 12.7%, respectively, with a 99.7% reduction in computational cost. Qualitatively, the advecting 0D PSR map produced a profile similar to the baseline LES map in shape and region of highest ignition probability with exception to the left wall region due to the effects of flame kernel growth. Overall, the low-order models serve well as a preliminary assessment of ignition probability by finding ignition locations where higher fidelity simulations can then be focused.
Small-scale turbulent characteristics in transcritical wall-bounded flows

Fangbo Li, Weiwei Zhang, Bofeng Bai, and Matthias Ihme

Journal of Fluid Mechanics, May 2024

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Considerable efforts have been devoted to the understanding of the small-scale characteristics in turbulent flows. While the universality of small-scale quantities has been established for incompressible flows, their extension to high-pressure transcritical flows remains an open area of research. To address this question, we investigate the real-fluid thermodynamic effects on small-scale velocity statistics of high-pressure transcritical wall-bounded turbulence. We show that in the locally isotropic region for transcritical flows, low-order moments of small-scale statistics collapse for all cases and Kolmogorov’s (1941) theory holds. However, real-fluid thermodynamic effects introduce deviations in the tails of the probability density function for the velocity derivative and, consequently, high-order moments of velocity gradients and dissipation rate in transcritical flows cannot collapse in the locally isotropic region. Analysis of the intermittency shows that the low-order structure functions in transcritical flows follow extended self-similarity, while the dependence of the intermittency factor on real-fluid effects is observed for high-order structure functions. The real-fluid effects on intermittency are explained by turbulent structures related to rare events. Additionally, the dissipation rate moments for transcritical flows follow a universal scaling with Reynolds number, and the scaling exponents are different from those of incompressible flows. These results extend the small-scale universality in incompressible flows (Schumacher et al., Proc. Natl Acad. Sci. USA, vol. 111, 2014, pp. 10961–10965) to realistic flows with significant changes in thermodynamic properties, and provide a physical underpinning of the scaling laws of small-scale statistics at transcritical conditions.
Analysis of direct and indirect noise in a next-generation aviation gas turbine combustor

Davy Brouzet, Benyamin Krisna, Duane McCormick, C Aaron Reimann, Jeff Mendoza, and Matthias Ihme

Combustion and Flame, Feb 2024

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A large-eddy simulation (LES) of a next-generation combustor is performed to examine effects of this combustor concepts on direct and indirect combustion noise characteristics. Direct noise is computed considering the unsteady heat release predictions while entropy fluctuations in the downstream part of the combustor are used to estimate indirect noise through the transfer function of the outlet nozzle. A low-order acoustic reconstruction technique, which utilizes the Green’s function of the configuration, is developed to compute the acoustics inside the combustor. Comparisons to experimental results are reported, showing the reasonable accuracy of the LES and combustion noise computations. The direct noise spectrum peaks at frequencies around 3 kHz because of the fast timescales associated with the chemical reactions inside the combustor. In addition, the indirect noise is dominant at low frequencies, i.e., less than 400 Hz, because of the characteristics of the entropy spectrum at the outlet nozzle. Compared to a conventional rich-quench-lean (RQL) combustor configuration, significant differences in the acoustics are observed, and are explained by two specific technological novelties. Firstly, the direct noise spectrum peaks at significantly higher frequencies due to the combustor’s compactness. Secondly, the entropy inhomogeneities downstream of the combustion region are an order of magnitude smaller in amplitude due to the lack of dilution with cold air. This leads to a significant reduction in the indirect noise amplitude at low frequencies, where it is the dominant source of noise. These results suggest opportunities for advanced combustion technologies to achieve substantial reductions in combustion-related noise.
Analysis of ducted fuel injection at high-pressure transcritical conditions using large-eddy simulations

Jack Guo, Davy Brouzet, Wai Tong Chung, and Matthias Ihme

International Journal of Engine Research, Feb 2024

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Ducted fuel injection (DFI) is a proposed fuel injection concept for achieving substantial reductions in emissions. In this concept, the fuel is injected through a coannular duct, resulting in increased fuel-air mixing and minimized formation of soot and other unwanted combustion products. Apart from comprehensive experimental investigations on DFI, so far computational studies have been limited to single-point Reynolds-averaged Navier Stokes simulations. Therefore, the objective of this work is to complement these studies by performing large-eddy simulations using a diffuse-interface method to examine the physical mechanisms and combustion processes of DFI, specifically focusing on the mixing process and the effect of fuel-ducting on combustion and pollutant emissions. To this end, finite-rate chemistry simulations are performed of the DFI configuration corresponding to the Engine Combustion Network Spray A injector at transcritical conditions (n-dodecane fuel, 60 bar pressure and 1000 K temperature chamber conditions). A two-equation soot model is employed for the qualitative analysis of soot emissions. Direct comparisons of averaged and instantaneous flow field results with the Spray A configuration are performed to assess the effect of DFI on the first- and second-stage ignition and soot formation. Compared to the free-spray condition, the results show that the DFI case exhibits a combination of (i) increased mass flow rate and entrained air, (ii) larger pressure drop magnitude and flow velocity, and (iii) a closer-to-stoichiometric mixture composition (both globally and locally), each of which is conjectured to contribute toward reduced soot production.
Approximately pressure-equilibrium-preserving scheme for fully conservative simulations of compressible multi-species and real-fluid interfacial flows

Hiroshi Terashima, Nguyen Ly, and Matthias Ihme

Journal of Computational Physics, Dec 2024

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This study proposes a numerical method for fluid interfaces in compressible multi-species and real-fluid flow simulations. The proposed method preserves the full conservation (species-mass, momentum, and energy) property of compressible flow equations while approximately maintaining the pressure equilibrium condition at fluid interfaces. The numerical fluxes of internal energy and species-mass are newly constructed to satisfy the pressure equilibrium condition approximately. The modified equation for the pressure equilibrium condition shows that the proposed numerical fluxes introduce different coefficients in the second-order error term, compared to standard numerical fluxes, thereby reducing the pressure equilibrium error. The conservation and pressure equilibrium properties of the proposed method are validated through one-dimensional and two-dimensional smooth interface advection problems using the compressible multi-species Euler equations with the Soave-Redlich-Kwong equation of state.
Analysis of weak secondary waves in a rotating detonation engine using large-eddy simulation and wavenumber-domain filtering

Guillaume Vignat, Davy Brouzet, Matthew Bonanni, and Matthias Ihme

Combustion and Flame, Mar 2024

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Rotating detonation engines (RDEs) are pressure-gain combustion devices which allow for a compact and mechanically simple engine design with improved thermodynamic efficiency compared to traditional deflagration devices. However, achieving these gains in practical devices that are operated with non-premixed reactants requires overcoming non-idealities in the mixing and combustion process. We investigate these non-ideal effects in the Air Force Research Laboratory’s rotating detonation rocket engine using large-eddy simulation. The simulation results are compared against experimental measurements, showing overall reasonable agreement for critical performance metrics of thrust, specific impulse, and chamber pressure. A wavenumber-domain filtering method is presented to separate the clockwise-rotating waves and counter-clockwise waves, which enables the unambiguous identification of secondary weak waves and their interaction with detonation waves. The analysis of the flow field and response of the injectors shows that these interactions lead to precessing regions of higher pressure, characterized by less parasitic combustion, higher heat release rate, and higher injector blockage. Furthermore, the thrust contributed by the pressure gain combustion process during these interactions is significantly increased, which leads to a modulation of the overall thrust output of the engine.
Mixtures Recomposition by Neural Nets: A Multidisciplinary Overview

Andre Nicolle, Sili Deng, Matthias Ihme, Nursulu Kuzhagaliyeva, Emad Al Ibrahim, and Aamir Farooq

Journal of Chemical Information and Modeling, Jan 2024

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Artificial Neural Networks (ANNs) are transforming how we understand chemical mixtures, providing an expressive view of the chemical space and multiscale processes. Their hybridization with physical knowledge can bridge the gap between predictivity and understanding of the underlying processes. This overview explores recent progress in ANNs, particularly their potential in the ’recomposition’ of chemical mixtures. Graph-based representations reveal patterns among mixture components, and deep learning models excel in capturing complexity and symmetries when compared to traditional Quantitative Structure–Property Relationship models. Key components, such as Hamiltonian networks and convolution operations, play a central role in representing multiscale mixtures. The integration of ANNs with Chemical Reaction Networks and Physics-Informed Neural Networks for inverse chemical kinetic problems is also examined. The combination of sensors with ANNs shows promise in optical and biomimetic applications. A common ground is identified in the context of statistical physics, where ANN-based methods iteratively adapt their models by blending their initial states with training data. The concept of mixture recomposition unveils a reciprocal inspiration between ANNs and reactive mixtures, highlighting learning behaviors influenced by the training environment.
A Normal-Score Ensemble Kalman Filter for 1D Shock Waves

James J Hansen, Davy Brouzet, and Matthias Ihme

In AIAA SCITECH 2024 Forum, Jan 2024

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A normal-score ensemble Kalman filter (NS-EnKF) formulation was developed and implemented to evaluate performance in assimilating observations into non-linearly evolving, non-Gaussian distributed systems. The NS-EnKF was benchmarked against the stochastic ensemble Kalman filter (EnKF) without localization on the Lorenz-96 system. Each filter was run for 100 stochastic trials with 10, 25, and 100 ensemble members. Compared to the EnKF, assimilation of 10 and 25 ensemble members with the NS-EnKF generated predictions which were more stable and had lower state prediction errors. When 100 ensemble members were used, the EnKF had lower prediction error on average while the NS-EnKF continued to offer greater solution stability. Filters were also compared using a numerical shock tube configuration with uncertainty in initial pressures and temperatures. Several trials were run to assimilate sparse pressure observations with varying measurement error into pressure, temperature, and velocity fields. While the relative performance of the EnKF and NS-EnKF varied with the assumed measurement error, both filters improved predictions of shock location as well as pressure, temperature and velocity fields. Results indicate that the NS-EnKF can provide superior prediction accuracy to the EnKF in cases where non-Gaussian distributed states are prevalent, but that further study is required to determine the value of the NS-EnKF in improving state prediction for shock-related applications.
Ensemble predictions of laser ignition with a hybrid stochastic physics-embedded deep-learning framework

Wai Tong Chung, Charlélie Laurent, Donatella Passiatore, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2024

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When investigating stochastic ignition phenomena, high-fidelity simulations and experiments for statistical characterization can be a laborious endeavor. Machine learning (ML), in particular deep-learning, offers an accurate and cost-effective approach for reduced-order modeling of forced ignition. In this work, we investigate the potential and limitations of ML in modeling ignition, especially in the presence of limited data and multiple ignition modes. To this end, we introduce a hybrid stochastic physics-embedded deep-learning framework that combines sparse experimental data from Schlieren measurements with inert large-eddy simulations for predicting the spatio-temporal evolution of ignition kernel location and morphology. This model combines a stochastic differential equation for modeling kernel dynamics and a deep-learning model for representing kernel morphology. We evaluate this modeling approach for laser ignition of a gaseous methane/oxygen (CH4/O2) model rocket combustor, where morphological effects of the ignition kernel significantly influence ignition behavior. Results demonstrate that this model can reasonably capture behavior associated with the three dominant ignition modes, namely direct, indirect, and failed ignition, along with statistics associated with kernel growth and position, at lower computational costs than high-fidelity reacting simulations. In addition, we demonstrate that this modeling framework can be employed for generating spatially resolved ignition probability maps by incorporating physics to represent kernel interaction with the turbulent jet. We note that limitations in accuracy can be observed when predicting with vastly out-of-distribution data. Nevertheless, these results demonstrate that this physics-embedded ML approach can statistically characterize forced ignition in a more cost-effective manner than reacting high-fidelity simulations, as long as sufficiently representative data is available.
Artificial intelligence as a catalyst for combustion science and engineering

Matthias Ihme, and Wai Tong Chung

Proceedings of the Combustion Institute, Aug 2024

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Combustion and energy conversion play critical roles in all facets of environmental and technological applications, including the utilization of sustainable energy sources for power generation and propulsion, the reduction of pollutant emissions from combustion, or the mitigation of harm from wildfire hazards. Computational and mathematical tools have long been crucial in combustion research in the form of high-fidelity simulations, dynamical-system modeling, and data analytics. With the advent of data-driven methods, machine learning (ML) and artificial intelligence (AI) offer numerous opportunities for predictive modeling, improving existing research methods, and extracting new knowledge from data. In this article, we discuss recent progress on how ML and AI can impact the field of combustion and energy conversion, and discuss the need for domain knowledge for successful ML applications in combustion. Specifically, combustion ML learns from data extracted from large-scale simulations, high-resolution experiments, and sensors, which can introduce challenges tied to dimensionality, interpretability, sparsity, modality, and scarcity. The collective knowledge from these advancements equip combustion researchers and engineers with the ability to adapt to emerging developments in ML foundation models and AI agents, which have begun to offer greater automation across different combustion domains. To this end, we assess opportunities and challenges provided by state-of-the-art ML foundation models, and discuss emerging areas for adapting these new technologies towards solving pressing challenges within sustainable combustion.
Experimental demonstration of a two-stage porous media burner for low-emission ammonia combustion

Guillaume Vignat, Thorsten Zirwes, Émeric Boigné, and Matthias Ihme

Proceedings of the Combustion Institute, Aug 2024

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Ammonia (NH3) is a carbon-free fuel that is projected to play a crucial role in reducing the environmental footprint of heavy industries and power generation. Retrofitting existing plants originally designed to operate with hydrocarbons is however challenging as NH3/air flames tend to emit higher levels of nitrogen oxides (NOx) and are more difficult to stabilize. Porous-media combustion has been shown to be an attractive technology to address flame stabilization challenges with fuel-flexible operation and reduced emissions. In the present work, we address high pollutant emissions in NH3 flames by proposing a two-stage, rich-quench-lean burner architecture, implemented using open-cell ceramic foams with a pore-size-graded topology. We found that this two-stage burner offers substantial improvements in terms of both NOx and NH3 emissions compared to a one-stage burner operated at the same mass flux and thermal power. The effect of operating conditions on emissions was systematically characterized, showing that an equivalence ratio of 1.2 in the primary zone and 0.8 in the secondary zone is optimal, with 15% O2 normalized NOx emissions of 28 ppmv and unburnt NH3 emissions of 149 ppmv, respectively. By using dispersion to promote mixing between the primary zone’s outflow and the secondary injection, the graded ceramic foam in the secondary combustion zone provided further emission reduction, 40% for NOx and 65% for unburnt NH3, respectively, compared to a more conventional cross-flow secondary air injection. To complement these experimental investigations, we performed 1D simulations in order to quantify conversion rates and effects of the secondary combustion zone on the emissions, revealing that a balance between low NO production and high NH3 cracking in the primary zone, and low slippage within the secondary zone, must be achieved to achieve low emissions.
Augmenting filtered flame front displacement models for LES using machine learning with a posteriori simulations

Jen Zen Ho, Mohsen Talei, Davy Brouzet, Wai Tong Chung, Pushan Sharma, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2024

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The Flame Surface Density (FSD) model is an affordable combustion model that has been widely used in simulating turbulent premixed flames. In Large Eddy Simulations (LES) with FSD, the combined effect of reaction and diffusion is governed by the Filtered Flame Front Displacement (FFFD) term. While the existing modelling approaches for this term are computationally cost-effective, their predictions still show inconsistencies in certain cases. This study aims to address these inconsistencies by generating Machine Learning (ML) models for the FFFD and FSD terms using the DNS data of a turbulent premixed jet flame. With this approach, the relevance of certain input parameters as well as certain modelling assumptions used for the FFFD term are assessed. Overall, it is found that the resolved curvature term is the most important input parameter to consider and that the resolved progress variable should also be considered in the models. It is shown that the ML models perform significantly better than legacy, algebraic formulations using a priori testing. To further assess the performance of ML, one of the ML models is employed in a a posteriori LES and compared against simulations with the algebraic model. The ML simulation is stable and yields encouraging improvements on key physical parameters regarding the flame length and the FFFD distribution.
Predictions of instantaneous temperature fields in jet-in-hot-coflow flames using a multi-scale U-Net model

Jordan AC Kildare, Wai Tong Chung, Michael J Evans, Zhao F Tian, Paul R Medwell, and Matthias Ihme

Proceedings of the Combustion Institute, Jul 2024

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A multi-scale U-Net machine learning (ML) model is developed to assess its validity as a surrogate for non-intrusive flame temperature measurement in jet-in-hot-coflow (JHC) flames. Inputs to the model are simultaneous hydroxyl (OH) and formaldehyde (CHO) planar laser-induced fluorescence (PLIF) measurements, with target temperature fields derived from Rayleigh scattering measurements. Coflow oxygen (O) concentration, jet Reynolds number, coflow temperature, and fuel inputs were considered in the dataset, resulting in 33 unique flame conditions, and 17,000 training images. The ML model reconstructs the instantaneous temperature images to within an absolute error of 7 ± 10% of the measured values for the initial natural gas/ethylene model. Transfer learning was employed to accelerate training across conditions of different fuels, with mean absolute reconstruction error of 7 ± 9% for models of ethanol and dimethyl ether. A fourth model including data from all four fuels was trained using transfer learning, with 6 ± 9% error. Multi-layer perceptron (MLP) classification models were applied to the deepest layers of the four-fuel model to identify whether physical and chemical flame features were being encoded. Experimentally verifiable features were found to be encoded within the latent space of the model, demonstrating that it is not solely an image regression tool, but is capable of predicting flame features including the fuel type, initial coflow temperature, downstream axial location, and coflow O concentration. These findings indicate that the model is not only well suited for temperature predictions, but can provide scientific insight as well.
A versatile pressure-cell design for studying ultrafast molecular-dynamics in supercritical fluids using coherent multi-pulse x-ray scattering

Priyanka Muhunthan, Haoyuan Li, Guillaume Vignat, Edna R Toro, Khaled Younes, Yanwen Sun, Dimosthenis Sokaras, Thomas Weiss, Ivan Rajkovic, Taito Osaka, Ichiro Inoue, Sanghoon Song, Takahiro Sato, Diling Zhu, John L Fulton, and Matthias Ihme

Review of Scientific Instruments, Jan 2024

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Supercritical fluids (SCFs) can be found in a variety of environmental and industrial processes. They exhibit an anomalous thermodynamic behavior, which originates from their fluctuating heterogeneous micro-structure. Characterizing the dynamics of these fluids at high temperature and high pressure with nanometer spatial and picosecond temporal resolution has been very challenging. The advent of hard x-ray free electron lasers has enabled the development of novel multi-pulse ultrafast x-ray scattering techniques, such as x-ray photon correlation spectroscopy (XPCS) and x-ray pump x-ray probe (XPXP). These techniques offer new opportunities for resolving the ultrafast microscopic behavior in SCFs at unprecedented spatiotemporal resolution, unraveling the dynamics of their micro-structure. However, harnessing these capabilities requires a bespoke high-pressure and high-temperature sample system that is optimized to maximize signal intensity and address instrument-specific challenges, such as drift in beamline components, x-ray scattering background, and multi-x-ray-beam overlap. We present a pressure cell compatible with a wide range of SCFs with built-in optical access for XPCS and XPXP and discuss critical aspects of the pressure cell design, with a particular focus on the design optimization for XPCS.
Examining diesel-spray assisted ignition of ammonia under reactivity-controlled conditions using large-eddy simulations

Pushan Sharma, Davy Brouzet, Wai Tong Chung, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2024

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Ammonia (NH3) has gained increasing attention as a promising carbon-free fuel for compression ignition engines. Nonetheless, its poor combustion characteristics and elevated nitrogen oxides (NOx) emissions present substantial obstacles. In the present study, we examine the utility of incorporating NH3 as a low-reactivity fuel (LRF) in diesel-assisted dual-fuel combustion under Reactivity Controlled Compression Ignition (RCCI) conditions. Three large-eddy simulations (LES) are performed to quantify the effect of varying concentrations of NH3 as LRF on the ignition characteristics and flame structure. The computational setup corresponds to the Engine Combustion Network (ECN) Spray A configuration, which provides the baseline for the present analysis. The ignition of the dodecane spray is found to be delayed by the presence of NH3, which increases with increasing NH3 content in the ambient. Local flamelets are extracted to examine the evolution of the flame structure starting from ignition at richer mixtures through low-temperature chemistry of dodecane, to finally stabilizing at the stoichiometric conditions. Near ignition, NH3 oxidation is observed to follow the autoignition behavior of the most reactive mixture fraction, whereas at post-ignition the behavior shifts towards canonical premixed flame propagation. This study shows that using NH3 as LRF under RCCI conditions offers an effective solution for NH3 operation in CI engines to reduce carbon emissions.
Coupling of detonation structure and upstream inhomogeneities in a rotating detonation engine

Matthew Bonanni, Davy Brouzet, Guillaume Vignat, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2024

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Rotating detonation rocket engines (RDREs) exhibit significant inhomogeneities in reactant composition upstream of their azimuthally-propagating detonation waves. These inhomogeneities impact performance characteristics of the combustor, as well as complicate the modeling of these systems. This work presents an analysis of a large-eddy simulation of a laboratory-scale RDRE, which resolves many of the inhomogeneities associated with scalar mixing and turbulent combustion. Lagrangian tracer particles are used as an analytical tool to track Eulerian state data, enabling extraction of detonation properties. Using this method, we show that the significant preburning present in this combustor is correlated with lower pressure ratios across the detonation front, consistent with prior results. Furthermore, we show that the detonation wave is distorted by these inhomogeneities into a non-planar shape. This distortion is indicative of pronounced detonation speed variations across the wave front, which is caused by upstream inhomogeneities and leads to the variation in pressure ratio. Finally, the detonation induces recirculation zones, which transport combustion products to the base of the combustor, thereby coupling to the upstream inhomogeneity of the next passing wave.
Analysis of residence time distribution in a cavity-stabilized scramjet combustor

Matthew Bonanni, Andrew Norris, and Matthias Ihme

Proceedings of the Combustion Institute, Aug 2024

Abs DOI

Controlling the competing temporal scales of advection, mixing, and combustion is critical to maintaining combustion stability in supersonic combustors, where the high free-stream velocity reduces their separation. Flameholding devices, such as cavities, locally increase the residence time by setting up recirculation zones in the flow where combustion may occur. In this work, we use Lagrangian particle analysis to examine the residence time distribution (RTD). We show that that the distribution of time for a single recirculation in the cavity follows an inverse Gaussian function, with a mean dependent on large-scale circulation and a variance dependent on turbulent velocity fluctuations. Using the RTD, a low-order model is then developed that employs a partially-stirred reactor to predict the combustion in the scramjet cavity. This low-order model is used to perform a parametric study, revealing that the stability of combustion depends not only on the mean residence time but also on the shape of the RTD. Combustion may be achieved in reactors with low mean residence times via a sufficiently skewed RTD. These results have implications for improved flameholder designs with less energy loss.
Experiment and modeling of stochastic ignition and combustion of fuel droplets impacting a hot surface

Nguyen Ly, Yichi Ma, Guillaume Vignat, Nozomu Hashimoto, and Matthias Ihme

Proceedings of the Combustion Institute, Aug 2024

Abs DOI

The ignition dynamic of liquid fuel droplets impacting hot surfaces is critical for fire-safety analysis in engineering systems, as well as for controlling wall-filming effects in IC engines. The scenario of slow fuel-leakage rates poses challenges associated with the stochastic processes of droplet splashing, break-up, turbulent mixing, and combustion. To address this, we conduct controlled experiments of liquid n-heptane droplets impacting a heated surface in the Leidenfrost regime, targeting the individual-droplet-deposition conditions. The experiment encompasses a range of surface temperatures and droplet-deposition rates. The experiments are complemented by theoretical analysis, where we developed a stochastic low-order numerical model, demonstrating good accuracy for predicting ignition probability and overall combustion dynamics. Notably, we observe a broad region of intermittent combustion behavior, with ignition probability varying based on surface temperature and droplet deposition rate. Additionally, we find that the transition to consistent ignition relies heavily on both surface temperature and deposition rate. Experimental and numerical model results shed light on the roles of the complex interplay between droplet breakup, chemical kinetics, and evaporation and mixing time scales, as well as the interaction among subsequent droplet combustion events, in governing the ignition and combustion of impacting droplet trains. The revealed dynamic of droplet/hot-surface ignition and the proposed stochastic model hold promise for advancing predictive capabilities of hot-surface-induced ignition and combustion arising from accidental leaks in flammable-liquid piping and wall-filming, particularly in the stochasticity-dominated individual-droplet-deposition regime.
Integrated experimental and computational analysis of porous media combustion by combining gas-phase synchrotron \muCT, IR-imaging, and pore-resolved simulations

Emeric Boigné, Thorsten Zirwes, Dilworth Y Parkinson, Guillaume Vignat, Priyanka Muhunthan, Harold S Barnard, Alastair A MacDowell, and Matthias Ihme

Combustion and Flame, Jan 2024

Abs DOI

Porous media combustion is a promising combustion technology that enables operation over an extended range of conditions, with a variety of fuels and low pollutant emissions. However, the lack of understanding of the interstitial combustion processes remains a major obstacle towards the application of this technology and the development of predictive models. To understand these processes, this study presents an integrated experimental and computational effort to examine porous media combustion. Specifically, a new experimental diagnostic method is employed that simultaneously combines synchrotron X-ray micro-computed tomography (CT) and short-wavelength infrared thermometry. With this approach, the surface temperature and the 3D gas-phase temperature field are simultaneously measured inside a porous burner with micrometer spatial resolution. These measurements are then integrated into 3D pore-resolved simulations. This integrated approach enables a direct evaluation of current modeling capabilities, and a unique analysis of interstitial combustion in porous foams under realistic heating conditions. In light of these results, we discover that about 80% of the fuel consumption inside the matrix pores occurs far enough from the porous surface to be characteristic of a decoupled regime of preheated, but adiabatic flamelets. The remaining fuel consumption near the pore surface occurs in a non-adiabatic combustion mode. This insight and the proposed approach contribute to our fundamental understanding of porous media combustion, and suggest that multi-regime models could more accurately describe porous burners.
A high-order diffused-interface approach for two-phase compressible flow simulations using a discontinuous Galerkin framework

Niccolò Tonicello, and Matthias Ihme

Journal of Computational Physics, Apr 2024

Abs DOI

A diffused-interface approach based on the Allen-Cahn phase field equation is developed within a high-order discontinuous Galerkin framework. The interface capturing technique is based on the balance between explicit diffusion and sharpening terms in the phase field equation, where the former term involves the computation of the local interface normal vectors. Due to the well-known Gibbs phenomenon encountered in high-order discretisations, the accurate evaluation of the normal vectors requires special consideration. To this end, a non-linear preconditioning strategy is proposed where an additional smooth level-set function, advected by the velocity field, is used for the evaluation of the normal vectors. It is shown that for appropriate choices of numerical fluxes and parameters of the model, the phase field remains bounded without any need for explicit regularisation. In order to preserve isolated interfaces, a quasi-conservative discretisation of the five-equation model is employed. A series of numerical experiments of increasing complexity are performed in order to assess the accuracy and robustness of the developed methodology, including two-phase flows involving viscous effects, gravitational forces, and surface tension.

2023

A high-resolution large-eddy simulation framework for Wildland Fire predictions using TensorFlow

Qing Wang, Matthias Ihme, Rod R. Linn, Yi-Fan Chen, Vivian Yang, Fei Sha, Craig Clements, Jenna S. McDanold, and John Anderson

International Journal of Wildland Fire, Oct 2023

DOI
Turbulence in focus: benchmarking scaling behavior of 3D volumetric super-resolution with BLASTNet 2.0 data

Wai Tong Chung, Bassem Akoush, Pushan Sharma, Alex Tamkin, Ki Sung Jung, Jacqueline H. Chen, Jack Guo, Davy Brouzet, Mohsen Talei, Bruno Savard, Alexei Y. Poludnenko, and Matthias Ihme

In Proceedings of the 37th International Conference on Neural Information Processing Systems, New Orleans, LA, USA, Dec 2023

Abs

Analysis of compressible turbulent flows is essential for applications related to propulsion, energy generation, and the environment. Here, we present BLASTNet 2.0, a 2.2 TB network-of-datasets containing 744 full-domain samples from 34 high-fidelity direct numerical simulations, which addresses the current limited availability of 3D high-fidelity reacting and non-reacting compressible turbulent flow simulation data. With this data, we benchmark a total of 49 variations of five deep learning approaches for 3D super-resolution - which can be applied for improving scientific imaging, simulations, turbulence models, as well as in computer vision applications. We perform neural scaling analysis on these models to examine the performance of different machine learning (ML) approaches, including two scientific ML techniques. We demonstrate that (i) predictive performance can scale with model size and cost, (ii) architecture matters significantly, especially for smaller models, and (iii) the benefits of physics-based losses can persist with increasing model size. The outcomes of this benchmark study are anticipated to offer insights that can aid the design of 3D super-resolution models, especially for turbulence models, while this data is expected to foster ML methods for a broad range of flow physics applications. This data is publicly available with download links and browsing tools consolidated at https://blastnet.github.io.
Accelerating Large-Eddy Simulations of Clouds With Tensor Processing Units

Sheide Chammas, Qing Wang, Tapio Schneider, Matthias Ihme, Yi-fan Chen, and John Anderson

Journal of Advances in Modeling Earth Systems, Oct 2023

DOI
On the noise analysis of a N+3 next-generation combustor through LES

Davy Brouzet, Matthias Ihme, Duane McCormick, Craig A. Reimann, and Jeff Mendoza

In AIAA Aviation 2023 Forum, Oct 2023

DOI
Adaptive Modeling of Supersonic Combustion in a Cavity-Stabilized Scramjet

Matthew Bonanni, and Matthias Ihme

In AIAA Scitech 2023 Forum, Oct 2023

DOI
Local Rearrangement in Adsorption Layers of Nanoconfined Ethane

Filip Simeski, Jiyue Wu, Sheng Hu, Theodore T. Tsotsis, Kristian Jessen, and Matthias Ihme

The Journal of Physical Chemistry C, Oct 2023

DOI
The Local Electronic Structure of Supercritical CO2 from X-ray Raman Spectroscopy and Atomistic-Scale Modeling

Priyanka Muhunthan, Oscar Paredes Mellone, Thomas Kroll, Dimosthenis Sokaras, and Matthias Ihme

The Journal of Physical Chemistry Letters, Oct 2023

DOI
Recurrent Convolutional Deep Neural Networks for Modeling Time-Resolved Wildfire Spread Behavior

John Burge, Matthew R. Bonanni, R. Lily Hu, and Matthias Ihme

Fire Technology, Aug 2023

DOI
Assessing requirements for modeling radiation in diffusion flames using an analytical, non-local model

Guilherme C. Fraga, Bifen Wu, Matthias Ihme, and Xinyu Zhao

Combustion and Flame, Sep 2023

DOI
Analysis of ducted fuel injection at high-pressure transcritical conditions using large-eddy simulations

Jack Guo, Davy Brouzet, Wai Tong Chung, and Matthias Ihme

International Journal of Engine Research, Sep 2023

DOI
Supercritical fluids behave as complex networks

Filip Simeski, and Matthias Ihme

Nature Communications, Apr 2023

DOI
Reaction nanoscopy of ion emission from sub-wavelength propanediol droplets

Philipp Rosenberger, Ritika Dagar, Wenbin Zhang, Arijit Majumdar, Marcel Neuhaus, Matthias Ihme, Boris Bergues, and Matthias F. Kling

Nanophotonics, Apr 2023

DOI
A Review of Physics-Informed Machine Learning in Fluid Mechanics

Pushan Sharma, Wai Tong Chung, Bassem Akoush, and Matthias Ihme

Energies, Apr 2023

DOI
Analysis of real-fluid thermodynamic effects on turbulent statistics in transcritical channel flows

Fangbo Li, Jack Guo, Bofeng Bai, and Matthias Ihme

Physical Review Fluids, Apr 2023

DOI
Corrosive Influence of Carbon Dioxide on Crack Initiation in Quartz: Comparison with Liquid Water and Vacuum Environments

Filip Simeski, and Matthias Ihme

Journal of Geophysical Research: Solid Earth, Apr 2023

DOI
Cost-constrained adaptive simulations of transient spray combustion in a gas turbine combustor

Danyal Mohaddes, Davy Brouzet, and Matthias Ihme

Combustion and Flame, Mar 2023

DOI
Wall heat transfer and flame structure transitions in stagnating spray flames

Danyal Mohaddes, and Matthias Ihme

Proceedings of the Combustion Institute, Mar 2023

DOI
LES of HCCI combustion of iso-octane/air in a flat-piston rapid compression machine

Wai Tong Chung, Nguyen Ly, and Matthias Ihme

Proceedings of the Combustion Institute, Mar 2023

DOI
Regimes of evaporation and mixing behaviors of nanodroplets at transcritical conditions

Nguyen Ly, Arijit Majumdar, and Matthias Ihme

Fuel, Mar 2023

DOI
Dynamics and structure of detonations in stratified product-gas diluted mixtures

Davy Brouzet, Guillaume Vignat, and Matthias Ihme

Proceedings of the Combustion Institute, Mar 2023

DOI
Jet-entrainment sampling: A new method for extracting particles from flames

Hope A. Michelsen, Emeric Boigné, Paul E. Schrader, K. Olof Johansson, Matthew F. Campbell, Ray P. Bambha, and Matthias Ihme

Proceedings of the Combustion Institute, Mar 2023

DOI
Combustion of lean ammonia-hydrogen fuel blends in a porous media burner

Guillaume Vignat, Bassem Akoush, Edna R. Toro, Emeric Boigné, and Matthias Ihme

Proceedings of the Combustion Institute, Mar 2023

DOI
Interaction of preferential evaporation and low-temperature chemistry in multicomponent counterflow spray flames

Matthew Bonanni, and Matthias Ihme

Proceedings of the Combustion Institute, Mar 2023

DOI

2022

A TensorFlow simulation framework for scientific computing of fluid flows on tensor processing units

Qing Wang, Matthias Ihme, Yi-Fan Chen, and John Anderson

Computer Physics Communications, May 2022

DOI
Enabling ultra-lean combustion of ammonia-hydrogen in porous media burners

Guillaume Vignat, Edna R. Toro, Émeric Boigné, Lauren Simitz, Bassem Akoush, Priyanka Muhunthan, and Matthias Ihme

In 2nd conference on low carbon combustion, Cambridge, UK, May 2022
Effect of preburn inhomogeneities on the detonation velocity in a rotating detonation rocket engine

Guillaume Vignat, Davy Brouzet, and Matthias Ihme

In 28th international colloquium on the dynamics of explosions and reactive systems, Napoli, Italy, May 2022
An Enrichment Wall Model for the Spectral Element Method

Steven R. Brill, Pinaki Pal, Muhsin Ameen, Chao Xu, and Matthias Ihme

In AIAA Scitech 2022 Forum, May 2022

DOI
Computing Thermodynamic Properties of Fluids Augmented by Nanoconfinement: Application to Pressurized Methane

Narendra Singh, Filip Simeski, and Matthias Ihme

The Journal of Physical Chemistry B, May 2022

DOI
Towards data-informed motion artifact reduction in quantitative CT using piecewise linear interpolation

Emeric Boigné, Dilworth Y. Parkinson, and Matthias Ihme

IEEE Transactions on Computational Imaging, May 2022

DOI
BLASTNet: A call for community-involved big data in combustion machine learning

Wai Tong Chung, Ki Sung Jung, Jacqueline H. Chen, and Matthias Ihme

Applications in Energy and Combustion Science, May 2022

DOI
The dynamics of non-premixed flames subjected to a transverse acoustic mode

Davy Brouzet, Shanni You, Miguel A. Plascencia, Mario Roa, and Matthias Ihme

Combustion and Flame, May 2022

DOI
Destabilization of binary mixing layer in supercritical conditions

Nguyen Ly, and Matthias Ihme

Journal of Fluid Mechanics, May 2022

Publisher: Cambridge University Press

DOI
Turbulence-induced bias in time-averaged laser absorption tomography of correlated concentration and temperature fields with a first-order correction

Chuyu Wei, Nikolaos Perakis, Daniel I. Pineda, Fokion N. Egolfopoulos, Matthias Ihme, and R. Mitchell Spearrin

Combustion and Flame, May 2022

DOI
Combustion machine learning: Principles, progress and prospects

Matthias Ihme, Wai Tong Chung, and Aashwin Ananda Mishra

Progress in Energy and Combustion Science, May 2022

DOI
Computation of hypersonic viscous flows with the thermally perfect gas model using a discontinuous Galerkin method

Eric J. Ching, Khalil Bensassi, Yu Lv, and Matthias Ihme

International Journal for Numerical Methods in Fluids, May 2022

DOI
Structure of the thermal boundary layer in turbulent channel flows at transcritical conditions

Jack Guo, Xiang I.A. Yang, and Matthias Ihme

Journal of Fluid Mechanics, May 2022

Publisher: Cambridge University Press

DOI
Parametric analysis of core-noise from a realistic gas-turbine combustor for cruise and take-off conditions

Changxiao Shao, Davy Brouzet, Nicholas Rock, and Matthias Ihme

Applications in Energy and Combustion Science, May 2022

DOI
On the hot surface ignition of a wall-stagnating spray flame

Danyal Mohaddes, and Matthias Ihme

Combustion and Flame, May 2022

DOI
Quail: A lightweight open-source discontinuous Galerkin code in Python for teaching and prototyping

Eric J. Ching, Brett Bornhoft, Ali Lasemi, and Matthias Ihme

SoftwareX, May 2022

DOI
Interpretable data-driven methods for subgrid-scale closure in LES for transcritical LOX/GCH4 combustion

Wai Tong Chung, Aashwin Ananda Mishra, and Matthias Ihme

Combustion and Flame, May 2022

DOI
Structural analysis of biomass pyrolysis and oxidation using in-situ X-ray computed tomography

Emeric Boigné, N Robert Bennett, Adam Wang, and Matthias Ihme

Combustion and Flame, May 2022

DOI

2021

Numerical Analyses of Transcritical Evaporation using Diffuse-Interface Method

Nguyen Ly, and Matthias Ihme

In International Conference on Liquid Atomization and Spray Systems (ICLASS), May 2021

Issue: 1

DOI
Evaluation of electron tomography reconstruction methods for a Barnett shale

Laura Frouté, Emeric Boigné, Matthias Ihme, and Anthony R. Kovscek

In Unconventional Resources Technology Conference, May 2021

DOI
Examining the effect of fire retardant on the combustion of wood via X-ray Computed Tomography

Emeric Boigné, N. Robert Bennett, Adam Wang, and Matthias Ihme

In 12th U. S. National Combustion Meeting, May 2021
Time integration considerations for the solution of reacting flows using discontinuous Galerkin methods

B. J. Bornhoft

In AIAA Scitech 2021 Forum, May 2021

DOI
Toward numerical investigation of ignition and combustion transition in a subscale LOX/methane rocket combustor

Matthew Bonanni, Danyal Mohaddes, Nguyen Ly, Nikolaos Perakis, Justin Hardi, Michael Börner, and Matthias Ihme

In AIAA Scitech 2021 Forum, May 2021

DOI
Development of a discontinuous Galerkin solver using Legion for heterogeneous high-performance computing architectures

Kihiro Bando, Steven Brill, Elliott Slaughter, Michael Sekachev, Alex Aiken, and Matthias Ihme

In AIAA Scitech 2021 Forum, May 2021

DOI
Analysis of core-noise contributions in a realistic gas-turbine combustor operated near lean blow-out

Changxiao Shao, Kazuki Maeda, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

DOI
Quantitative X-ray computed tomography: Prospects for detailed in-situ imaging in bench-scale fire measurements

Emeric Boigné, N Robert Bennett, Adam Wang, and Matthias Ihme

Fire Safety Journal, Jan 2021

Publisher: Elsevier

DOI
Infrasound radiation from impulsive volcanic eruptions: nonlinear aeroacoustic 2D simulations

Leighton M. Watson, Eric M. Dunham, Danyal Mohaddes, Jeff Labahn, Thomas Jaravel, and Matthias Ihme

Journal of Geophysical Research: Solid Earth, Jan 2021

Publisher: Elsevier

DOI
Heat transfer augmentation by recombination reactions in turbulent reacting boundary layers at elevated pressures

Nikolaos Perakis, Oskar Haidn, and Matthias Ihme

International Journal of Heat and Mass Transfer, Jan 2021

Publisher: Elsevier

DOI
Sensitivity of hypersonic dusty flows to physical modeling of the particle phase

Eric Ching, Michael Barnhardt, and Matthias Ihme

Journal of Spacecraft and Rockets, Jan 2021

Publisher: American Institute of Aeronautics and Astronautics

DOI
Analysis of droplet evaporation in isotropic turbulence through droplet-resolved DNS

Michael S. Dodd, Danyal Mohaddes, Antonino Ferrante, and Matthias Ihme

International Journal of Heat and Mass Transfer, Jan 2021

Publisher: Elsevier

DOI
Hot surface ignition of a wall-impinging fuel spray: Modeling and analysis using large-eddy simulation

Danyal Mohaddes, Philipp Boettcher, and Matthias Ihme

Combustion and Flame, Jan 2021

Publisher: Elsevier

DOI
Data-assisted combustion simulations with dynamic submodel assignment using random forests

Wai Tong Chung, Aashwin Ananda Mishra, Nikolaos Perakis, and Matthias Ihme

Combustion and Flame, Jan 2021

Publisher: Elsevier

DOI
Using adjoint-based optimization to enhance ignition in non-premixed jets

Ubaid Ali Qadri, Luca Magri, Matthias Ihme, and Peter J. Schmid

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Jan 2021

DOI
Imaging the short-lived hydroxyl-hydronium pair in ionized liquid water

Ming Fu Lin, Narendra Singh, Shujia Liang, Mianzhen Mo, João Pedro Figueira Nunes, Kathryn Ledbetter, Jie Yang, Michael Kozina, Stephen Weathersby, Xiaozhe Shen, Amy A. Cordones, Thomas J. A. Wolf, Das Pemmaraju, Matthais Ihme, and Xijie Wang

Science, Jan 2021

DOI
Pore-resolved simulations of porous media combustion with conjugate heat transfer

Joseph C Ferguson, Sadaf Sobhani, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI
Analysis of low-temperature chemistry in a turbulent swirling spray flame near lean blow-out

Danyal Mohaddes, Wenwen Xie, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI
Experimental feasibility of tailored porous media burners enabled via additive manufacturing

Sadaf Sobhani, Priyanka Muhunthan, Emeric Boigné, Danyal Mohaddes, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI
Simultaneous in-situ measurements of gas temperature and pyrolysis of biomass smoldering via X-ray computed tomography

Emeric Boigné, N Robert Bennett, Adam Wang, Khadijeh Mohri, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI
Kinetics for the hydrolysis of Ti (OC3H7) 4: A molecular dynamics simulation study

Jili Wei, Alireza Ostadhossein, Shuiqing Li, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI
Structural analysis and regime diagrams of laminar counterflow spray flames with low-temperature chemistry

Wenwen Xie, Pavan B Govindaraju, Zhuyin Ren, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI
Stability diagram and blow-out mechanisms of turbulent non-premixed combustion

Dong Li, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI
Investigation of CO recombination in the boundary layer of CH4/O2 rocket engines

Nikolaos Perakis, Oskar J Haidn, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2021

Publisher: Elsevier

DOI

2020

An Enriched Basis Discontinuous Galerkin Method for Shocks and High-Gradient Features in Fluid Mechanics

Steven Brill, and Matthias Ihme

In AIAA Scitech 2020 Forum, Jan 2020

DOI
Comparison of algorithms for simulating multi-component reacting flows using high-order discontinuous Galerkin methods

Kihiro Bando, Michael Sekachev, and Matthias Ihme

In AIAA Scitech 2020 Forum, Jan 2020

DOI
General Drag Coefficient for Flow over Spherical Particles

Narendra Singh, Michael Kroells, Chenxi Li, Eric Ching, Matthias Ihme, Christopher J. Hogan, and Thomas E. Schwartzentruber

AIAA Journal, Jan 2020

DOI
Modeling Adsorption in Silica Pores via Minkowski Functionals and Molecular Electrostatic Moments

Filip Simeski, Arnout M. P. Boelens, and Matthias Ihme

Energies, Jan 2020

Publisher: MDPI

DOI
Pareto-efficient combustion framework for predicting transient ignition dynamics in turbulent flames: Application to a pulsed jet-in-hot-coflow flame

Quentin Douasbin, Matthias Ihme, and Christoph Arndt

Combustion and Flame, Jan 2020

Publisher: Elsevier

DOI
Carbon oxidation in turbulent premixed jet flames: A comparative experimental and numerical study of ethylene, n-heptane, and toluene

Daniel I Pineda, Laurel Paxton, Nikolaos Perakis, Chuyu Wei, Steven Luna, Hiba Kahouli, Matthias Ihme, Fokion N Egolfopoulos, and R Mitchell Spearrin

Combustion and Flame, Jan 2020

Publisher: Elsevier

DOI
Thermodynamic cycle analysis of superadiabatic matrix-stabilized combustion for gas turbine engines

Danyal Mohaddes, Clarence T Chang, and Matthias Ihme

Energy, Jan 2020

Publisher: Elsevier

DOI
Between supercritical liquids and gases–reconciling dynamic and thermodynamic state transitions

Daniel T. Banuti, Muralikrishna Raju, and Matthias Ihme

The Journal of Supercritical Fluids, Jan 2020

Publisher: Elsevier

DOI
Additive Manufacturing of Tailored Macroporous Ceramic Structures for High-Temperature Applications

Sadaf Sobhani, Shawn Allan, Priyanka Muhunthan, Emeric Boigné, and Matthias Ihme

Advanced Engineering Materials, Jan 2020

DOI
Uncertainty quantification of combustion noise by generalized polynomial chaos and state-space models

Camilo F. Silva, Per Pettersson, Gianluca Iaccarino, and Matthias Ihme

Combustion and Flame, Jan 2020

DOI
StanShock: a gas-dynamic model for shock tube simulations with non-ideal effects and chemical kinetics

Kevin Grogan, and Matthias Ihme

Shock Waves, Jan 2020

Publisher: Springer

DOI

2019

Analysis of blow-out mechanisms of turbulent swirl-stabilized non-premixed flames

Dong Li, Thomas Jaravel, and Matthias Ihme

In 11th U. S. National Combustion Meeting, Jun 2019
Enabling Tailored Porous Media Burners via Additive Manufacturing

Sadaf Sobhani, Priyanka Muhunthan, Danyal Mohaddes, Emeric Boigné, Zhilong Cheng, and Matthias Ihme

In 11th U. S. National Combustion Meeting, Jun 2019
Requirements Towards Predictive Simulations of Turbulent Combustion

Matthias Ihme

In AIAA Scitech 2019 Forum, Jun 2019
Sensitivity study of high-speed dusty flows over blunt bodies simulated using a discontinuous Galerkin method

Eric J Ching, and Matthias Ihme

In AIAA Scitech 2019 Forum, Jun 2019
Compressible Flamelet Model with Thickened Flame Closure in an All-Speed Combustion Solver

Siddharth S Thakur, Jeffrey Wright, and Matthias Ihme

In AIAA Scitech 2019 Forum, Jun 2019
A two-way-coupled Euler-Lagrange method for simulating multiphase flows with discontinuous Galerkin schemes on arbitrary curved elements

Eric J Ching, Steven R Brill, Michael Barnhardt, and Matthias Ihme

Journal of Computational Physics, Jun 2019

Publisher: Elsevier

DOI
Ensemble Kalman filter for assimilating experimental data into large-eddy simulations of turbulent flows

Jeffrey W. Labahn, Hao Wu, Shaun R. Harris, Bruno Coriton, Jonathan H. Frank, and Matthias Ihme

Flow, Turbulence and Combustion, Jun 2019

Publisher: Springer

DOI
Experimental investigation of lean premixed pre-vaporized liquid-fuel combustion in porous media burners at elevated pressures up to 20 bar

Sadaf Sobhani, Justin Legg, David F Bartz, Jun J Kojima, Clarence T Chang, John D Sullivan, Jeffrey P Moder, and Matthias Ihme

Combustion and Flame, Jun 2019

Publisher: Elsevier Inc.

DOI
Functionalization of 2D materials for enhancing OER/ORR catalytic activity in Li–oxygen batteries

Alireza Ostadhossein, Jack Guo, Filip Simeski, and Matthias Ihme

Communications Chemistry, Jun 2019

ISBN: 2399-3669

DOI
Examination of diesel spray combustion in supercritical ambient fluid using large-eddy simulations

Wai Tong Chung, Peter C Ma, and Matthias Ihme

International Journal of Engine Research, Jun 2019

Publisher: SAGE Publications Sage UK: London, England

DOI
Efficient time-stepping techniques for simulating turbulent reactive flows with stiff chemistry

Hao Wu, Peter C. Ma, and Matthias Ihme

Computer Physics Communications, Jun 2019

DOI
A regularized deconvolution model for sub-grid dispersion in large eddy simulation of turbulent spray flames

Qing Wang, Xinyu Zhao, and Matthias Ihme

Combustion and Flame, Jun 2019

Publisher: Elsevier

DOI
On the numerical behavior of diffuse-interface methods for transcritical real-fluids simulations

Peter C Ma, Hao Wu, Daniel T Banuti, and Matthias Ihme

International Journal of Multiphase Flow, Jun 2019

Publisher: Elsevier

DOI
X-ray computed tomography for flame-structure analysis of laminar premixed flames

Emeric Boigné, Priyanka Muhunthan, Danyal Mohaddes, Qing Wang, Sadaf Sobhani, Waldo Hinshaw, and Matthias Ihme

Combustion and Flame, Jun 2019

Publisher: Elsevier

DOI
Error-controlled kinetics reduction based on non-linear optimization and sensitivity analysis

Thomas Jaravel, Hao Wu, and Matthias Ihme

Combustion and Flame, Jun 2019

Publisher: Elsevier

DOI
Shock capturing for discontinuous Galerkin methods with application to predicting heat transfer in hypersonic flows

Eric J Ching, Yu Lv, Peter Gnoffo, Michael Barnhardt, and Matthias Ihme

Journal of Computational Physics, Jun 2019

Publisher: Elsevier

DOI
Coupling of turbulence on the ignition of multicomponent sprays

Pavan B Govindaraju, Thomas Jaravel, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Numerical study of the ignition behavior of a post-discharge kernel in a turbulent stratified crossflow

Thomas Jaravel, Jeff Labahn, Brandon Sforzo, Jerry Seitzman, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

DOI
A new ignition time model applied to super knock

Kevin P Grogan, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Analysis of transient blow-out dynamics in a swirl-stabilized combustor using large-eddy simulations

Peter C Ma, Hao Wu, Jeffrey W Labahn, Thomas Jaravel, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Assessment of spray combustion models in large-eddy simulations of a polydispersed acetone spray flame

Qing Wang, Thomas Jaravel, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Pareto-efficient combustion modeling for improved CO-emission prediction in LES of a piloted turbulent dimethyl ether jet flame

Hao Wu, Peter C Ma, Thomas Jaravel, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Modulation of heat transfer for extended flame stabilization in porous media burners via topology gradation

Sadaf Sobhani, Danyal Mohaddes, Emeric Boigné, Priyanka Muhunthan, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Large-eddy simulations of transcritical injection and auto-ignition using diffuse-interface method and finite-rate chemistry

Peter C Ma, Hao Wu, Thomas Jaravel, Luis Bravo, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Data assimilation using high-speed measurements and LES to examine local extinction events in turbulent flames

Jeffrey W Labahn, Hao Wu, Bruno Coriton, Jonathan H Frank, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2019

Publisher: Elsevier

DOI
Large eddy simulations of diesel-fuel injection and auto-ignition at transcritical conditions

Matthias Ihme, Peter C Ma, and Luis Bravo

International Journal of Engine Research, Jun 2019

Publisher: SAGE Publications Sage UK: London, England

DOI

2018

Transcritical mixing and auto-ignition of n-dodecane fuel using a diffuse interface method

Luis G Bravo, Peter C Ma, Matthias Ihme, and Kevin A Kerner

In 2018 Joint Propulsion Conference, Jun 2018
Modeling of sub-grid dispersion in large-eddy simulation using regularized deconvolution method

Qing Wang, Xinyu Zhao, and Matthias Ihme

In 2018 AIAA Aerospace Sciences Meeting, Jun 2018
Direct numerical simulations of turbulent channel flow under transcritical conditions

Peter C Ma, Xiang Yang, and Matthias Ihme

In 2018 AIAA Aerospace Sciences Meeting, Jun 2018
Efficient time stepping for reactive turbulent simulations with stiff chemistry

Hao Wu, Peter C Ma, and Matthias Ihme

In 2018 AIAA Aerospace Sciences Meeting, Jun 2018
Development of a Lagrangian Particle Tracking Method for High-Order Discontinuous Galerkin Schemes

Eric Ching, Steven Brill, Yu Lv, and Matthias Ihme

In 2018 AIAA Aerospace Sciences Meeting, Jun 2018
Lyapunov exponent and Wasserstein metric as validation tools for assessing short-time dynamics and quantitative model evaluation of large-eddy simulation

Hao Wu, Peter C Ma, Yu Lv, and Matthias Ihme

In 2018 AIAA Aerospace Sciences Meeting, Jun 2018
Application of Pareto-efficient combustion modeling framework to large eddy simulations of turbulent reacting flows

Hao Wu, Peter C Ma, Thomas Jaravel, and Matthias Ihme

In 2018 AIAA Aerospace Sciences Meeting, Jun 2018
Numerical analysis on mixing processes for transcritical real-fluid simulations

Peter C Ma, Hao Wu, Daniel T Banuti, and Matthias Ihme

In 2018 AIAA Aerospace Sciences Meeting, Jun 2018
Computational modeling and analysis of Diesel-fuel injection and autoignition at transcritical conditions

Matthias Ihme, Peter C Ma, and Luis Bravo

arXiv e-prints, Sep 2018

_eprint: 1809.08721
Structure of wall-bounded flows at transcritical conditions

Peter C Ma, Xiang IA Yang, and Matthias Ihme

Physical Review Fluids, Sep 2018

Publisher: APS

DOI
Identification of governing physical processes of irregular combustion through machine learning

Kevin P. Grogan, and Matthias Ihme

Shock Waves, Sep 2018

Publisher: Springer

DOI
Assessment of differential diffusion effects in flamelet modeling of oxy-fuel flames

Sandro Gierth, Franziska Hunger, Sebastian Popp, Hao Wu, Matthias Ihme, and Christian Hasse

Combustion and Flame, Sep 2018

Publisher: Elsevier

DOI
Thermodynamic structure of supercritical LOX–GH2 diffusion flames

Daniel T Banuti, Peter C Ma, Jean-Pierre Hickey, and Matthias Ihme

Combustion and Flame, Sep 2018

Publisher: Elsevier

DOI
Nonadiabatic flamelet formulation for predicting wall heat transfer in rocket engines

Peter C. Ma, Hao Wu, Matthias Ihme, and Jean-Pierre Hickey

AIAA Journal, Apr 2018

ISBN: 0001-1452 Publisher: American Institute of Aeronautics and Astronautics

DOI
On underresolved simulations of compressible turbulence using an entropy-bounded DG method: solution stabilization, scheme optimization, and benchmark against a finite-volume solver

Yu Lv, Peter C Ma, and Matthias Ihme

Computers & Fluids, Apr 2018

Publisher: Elsevier

DOI
Formulation of optimal surrogate descriptions of fuels considering sensitivities to experimental uncertainties

Pavan B Govindaraju, and Matthias Ihme

Combustion and Flame, Apr 2018

Publisher: Elsevier

DOI
Atomistic and continuum scale modeling of functionalized graphyne membranes for water desalination

Muralikrishna Raju, Pavan B. Govindaraju, Adri C. T. Duin, and Matthias Ihme

Nanoscale, Apr 2018

Publisher: Royal Society of Chemistry

DOI
Phase transitions of ordered ice in graphene nanocapillaries and carbon nanotubes

Muralikrishna Raju, Adri Duin, and Matthias Ihme

Scientific Reports, Apr 2018

Abs DOI

New phase diagrams for water confined in graphene nanocapillaries and single-walled carbon nanotubes (CNTs) are proposed, identifying ice structures, their melting points and revealing the presence of a solid-liquid critical point. For quasi-2D water in nanocapillaries, we show through molecular-dynamics simulations that AA stacking in multilayer quasi-2D ice arises from interlayer hydrogen-bonding and is stable up to three layers, thereby explaining recent experimental observations. Detailed structural and energetic analyses show that quasi-2D water can freeze discontinuously through a first-order phase transition or continuously with a critical point. The first-order transition line extends to a continuous transition line, defined by a sharp transition in diffusivity between solid-like and liquid-like regimes. For quasi-1D water, confined in CNTs, we observe the existence of a similar critical point at intermediate densities. In addition, an end point is identified on the continuous-transition line, above which the solid and liquid phases deform continuously. The solid-liquid phase transition temperatures in CNTs are shown to be substantially higher than 273 K, confirming recent Raman spectroscopy measurements. We observe ultrafast proton and hydroxyl transport in quasi-1D and -2D ice at 300 K, exceeding those of bulk water up to a factor of five, thereby providing possible applications to fuel-cells and electrolyzers.
Generalized chaos expansion of state space modelsfor uncertainty quantification in thermoacoustics

Camilo F. Silva, Per Petersson, Gianluca Iaccarino, and Matthias Ihme

Proceedings of the Summer Program, Apr 2018

Publisher: Center for Turbulence Research
Physics-informed data-driven prediction ofpremixed flame dynamics with data assimilation

Hao Yu, Thomas Jaravel, Jeff Labahn, Matthias Ihme, Matthew P. Juniper, and Luca Magri

Proceedings of the Summer Program, Apr 2018

Publisher: Center for Turbulence Research
Direct numerical simulation, analysis, and modeling of the evaporation of multiple fueldroplets in a hot turbulent flow

Christophe Duwig, Giandomenico Lupo, Andrea Gruber, Luca Brandt, Pavan B. Govindaraju, Thomas Jaravel, and Matthias Ihme

Proceedings of the Summer Program, Apr 2018

Publisher: Center for Turbulence Research
Physics-based near-wall turbulence modeling in anenriched discontinuous Galerkin framework

Yu Lv, Xiang I.A. Yang, George I. Park, and Matthias Ihme

Proceedings of the Summer Program, Apr 2018

Publisher: Center for Turbulence Research
Large-scale space definition for the DG-VMS method based on energy transfer analyses

Fabio Naddei, Marta Llave Plata, Eric Lamballais, Vincent Couaillier, Marc Massot, and Matthias Ihme

Proceedings of the Summer Program, Apr 2018

Publisher: Center for Turbulence Research
Variational multiscale SGS modeling for LESusing a high-order discontinuous Galerkin method

Kihiro Bando, Fabio Naddei, Marta Llave Plata, and Matthias Ihme

Annual Research Briefs, Apr 2018

Publisher: Center for Turbulence Research
Thermal structures and heat transfer in wall-bounded flows at transcritical conditions

Jack Guo, Xiang I.A. Yang, and Matthias Ihme

Annual Research Briefs, Apr 2018

Publisher: Center for Turbulence Research

2017

A flamelet model with heat-loss effects for predicting wall-heat transfer in rocket engines

Peter C Ma, Hao Wu, Matthias Ihme, and Jean-Pierre Hickey

In 53rd AIAA/SAE/ASEE Joint Propulsion Conference, Apr 2017

DOI
Investigation of initial droplet distribution and importance of secondary breakup model on lean blowout predictions of a model gas turbine combustor

Jeffrey Labahn, Peter Chao Ma, Lucas Esclapez, and Matthias Ihme

In 10th U. S. National Combustion Meeting, Apr 2017
Modal Analysis of Direct Core Noise in a Model Combustor

Jeffrey O’Brien, Friedrich Bake, and Matthias Ihme

In 10th U.S. National Combustion Meeting, Apr 2017

Abs

Combustion noise is a growing concern for gas turbine designers, especially the presence of prominent tonal structures or thermoacoustic instabilities. High fidelity simulations such as compressible large eddy simulation (LES) have demonstrated great potential in predicting the behavior of these reacting flows, but these methods generate massive amounts of data and efficient techniques are required to isolate the behavior and underlying physics of acoustic structures. Multiple modaldecomposition techniques have gained prominence across a variety of fields for identifying the underlying dynamics of complex systems, including the fast Fourier Transform (FFT), proper orthogonal decomposition (POD), and dynamic mode decomposition (DMD). Here, these three techniques are applied to the pressure field taken from a compressible LES of a gas turbine model combustor (GTMC). Comparisons are made between the structures identified by each algorithm as well as the capacity of each technique to identify mode amplitude and assign cardinality to the modes. Lastly, comments are offered about the advantages and disadvantages, including robustness, of the methods studied.
Instability Analysis of the Separated Boundary Layer in Shock Tubes

Kevin P Grogan, and Matthias Ihme

In 55th AIAA Aerospace Sciences Meeting, Apr 2017
Modeling and simulation of the inlet mixing process in a rotating detonation engine

Kevin P Grogan, B. Rankin, and Matthias Ihme

In 10th U. S. National Combustion Meeting, Apr 2017
MVP-Workshop Contribution: Modeling of Volvo Bluff Flame Experiment and Comparison of Finite-Volume and Discontinuous-Galerkin Schemes

Hao Wu, Peter C Ma, Yu Lv, and Matthias Ihme

Apr 2017
Numerical framework for transcritical real-fluid reacting flow simulations using the flamelet progress variable approach

Peter C Ma, Daniel Banuti, Jean-Pierre Hickey, and Matthias Ihme

In 55th AIAA Aerospace Sciences Meeting, Apr 2017
Seven questions about supercritical fluids-towards a new fluid state diagram

Daniel Banuti, Muralikrishna Raju, Peter C Ma, Matthias Ihme, and Jean-Pierre Hickey

In 55th AIAA Aerospace Sciences Meeting, Apr 2017
Large-Eddy Simulations of Fuel Effect on Gas Turbine Lean Blow-out

Lucas Esclapez, Peter C Ma, Eric Mayhew, Rui Xu, Scott Stouffer, Tonghun Lee, Hai Wang, and Matthias Ihme

In 55th AIAA Aerospace Sciences Meeting, Apr 2017
Species dependency of the compositional indirect noise mechanism

Jeffrey D O’Brien, and Matthias Ihme

In Proceedings of ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, Apr 2017
Effects of nozzle Helmholtz number on indirect combustion noise by compositional perturbations

Luca Magri, Jeffrey O’Brien, and Matthias Ihme

In Proceedings of ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, Apr 2017
Investigation of Lean Combustion Stability, Pressure Drop, and Material Durability in Porous Media Burners

Sadaf Sobhani, Bret Haley, Dave Bartz, Jared Dunnmon, John Sullivan, and Matthias Ihme

In Proceedings of ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, Apr 2017
Lyapunov exponent as a metric for assessing the dynamic content and predictability of large-eddy simulations

Gabriel Nastac, Jeffrey W. Labahn, Luca Magri, and Matthias Ihme

Phys. Rev. Fluids, Sep 2017

Publisher: American Physical Society

DOI
Flamelet regime characterization for non-premixed turbulent combustion simulations

Wai Lee Chan, and Matthias Ihme

Combustion and Flame, Sep 2017

DOI
Numerical investigation of soot-flame-vortex interaction

Benedetta Franzelli, Alberto Cuoci, Alessandro Stagni, Matthias Ihme, Tiziano Faravelli, and Sebastian Candel

Proceedings of the Combustion Institute, Sep 2017

DOI
Regimes describing shock boundary layer interaction and ignition in shock tubes

Kevin P. Grogan, and Matthias Ihme

Proceedings of the Combustion Institute, Sep 2017

DOI
A general probabilistic approach for the quantitative assessment of LES combustion models

Ross Johnson, Hao Wu, and Matthias Ihme

Combustion and Flame, Sep 2017

Abs DOI

Abstract The Wasserstein metric is introduced as a probabilistic method to enable quantitative evaluations of {LES} combustion models. The Wasserstein metric can directly be evaluated from scatter data or statistical results through probabilistic reconstruction. The method is derived and generalized for turbulent reacting flows, and applied to validation tests involving a piloted turbulent jet flame with inhomogeneous inlets. It is shown that the Wasserstein metric is an effective validation tool that extends to multiple scalar quantities, providing an objective and quantitative evaluation of model deficiencies and boundary conditions on the simulation accuracy. Several test cases are considered, beginning with a comparison of mixture-fraction results, and the subsequent extension to reactive scalars, including temperature and species mass fractions of {CO} and CO2. To demonstrate the versatility of the proposed method in application to multiple datasets, the Wasserstein metric is applied to a series of different simulations that were contributed to the TNF-workshop. Analysis of the results allows to identify competing contributions to model deviations, arising from uncertainties in the boundary conditions and model deficiencies. These applications demonstrate that the Wasserstein metric constitutes an easily applicable mathematical tool that reduce multiscalar combustion data and large datasets into a scalar-valued quantitative measure.
Similarity law for Widom lines and coexistence lines

Daniel T. Banuti, Muralikrishna Raju, and Matthias Ihme

Phys. Rev. E, May 2017

Publisher: American Physical Society

DOI
High-order discontinuous Galerkin method for applications to multicomponent and chemically reacting flows

Yu Lv, and Matthias Ihme

Acta Mechanica Sinica, Jun 2017

Abs DOI

This article focuses on the development of a discontinuous Galerkin (DG) method for simulations of multicomponent and chemically reacting flows. Compared to aerodynamic flow applications, in which DG methods have been successfully employed, DG simulations of chemically reacting flows introduce challenges that arise from flow unsteadiness, combustion, heat release, compressibility effects, shocks, and variations in thermodynamic properties. To address these challenges, algorithms are developed, including an entropy-bounded DG method, an entropy-residual shock indicator, and a new formulation of artificial viscosity. The performance and capabilities of the resulting DG method are demonstrated in several relevant applications, including shock/bubble interaction, turbulent combustion, and detonation. It is concluded that the developed DG method shows promising performance in application to multicomponent reacting flows. The paper concludes with a discussion of further research needs to enable the application of DG methods to more complex reacting flows.
Combustion and engine-core noise

Matthias Ihme

Annual Review of Fluid Mechanics, Jun 2017

Publisher: Annual Reviews

DOI
The role of preferential evaporation on the ignition of multicomponent fuels in a homogeneous spray/air

Alessandro Stagni, Lucas Esclapez, Pavan Govindaraju, Alberto Cuoci, Tiziano Faravelli, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2017

DOI
The cross-scale physical-space transfer of kinetic energy in turbulent premixed flames

Jeffrey O’Brien, Colin A. Z. Towery, Peter E. Hamlington, Matthias Ihme, Y. Poludnenko, and Javier Urzay

Proceedings of the Combustion Institute, Jun 2017

DOI
Multiple-scale thermo-acoustic stability analysis of a coaxial jet combustor

Luca Magri, Yee Chee See, Outi Tammisola, Matthias Ihme, and Matthew P. Juniper

Proceedings of the Combustion Institute, Jun 2017

DOI
Classification and lift-off height prediction of non-premixed MILD and autoignitive flames

Michael J. Evans, Paul R. Medwell, Hao Wu, Alessandro Stagni, and Matthias Ihme

Proceedings of the Combustion Institute, Jun 2017

DOI
Development and Analysis of Wall Models for Internal Combustion Engine Simulations Using High-speed Micro-PIV Measurements

Peter C. Ma, Tim Ewan, Christopher Jainski, Louise Lu, Andreas Dreizler, Volker Sick, and Matthias Ihme

Flow, Turbulence and Combustion, Jan 2017

Abs DOI

The performance, efficiency and emissions of internal combustion (IC) engines are affected by the thermo-viscous boundary layer region and heat transfer. Computational models for the prediction of engine performance typically rely on equilibrium wall-function models to overcome the need for resolving the viscous boundary layer structure. The wall shear stress and heat flux are obtained as boundary conditions for the outer flow calculation. However, these equilibrium wall-function models are typically derived by considering canonical flow configurations, introducing substantial modeling assumptions that are not necessarily justified for in-cylinder flows. The objective of this work is to assess the validity of several model approximations that are commonly introduced in the development of wall-function models for IC-engine applications. This examination is performed by considering crank-angle resolved high-resolution micro-particle image velocimetry (µ-PIV) measurements in a spark-ignition direct-injection single cylinder engine. Using these measurements, the performance of an algebraic equilibrium wall-function model commonly used in RANS and LES IC-engine simulations is evaluated. By identifying shortcomings of this model, a non-equilibrium differential wall model is developed and two different closures are considered for the determination of the turbulent viscosity. It is shown that both wall models provide adequate predictions if applied inside the viscous sublayer. However, the equilibrium wall-function model consistently underpredicts the shear stress if applied in the log-layer. In contrast, the non-equilibrium wall model provides improved predictions of the near-wall region and shear stress irrespective of the wall distance and the piston location. By utilizing the experimental data, significant adverse pressure gradients due to the large vortical motion inside the cylinder (induced by tumble, swirl and turbulence) are observed and included in the non-equilibrium wall model to further improve the model performance. These investigations are complemented by developing a consistent wall heat transfer model, and simulation results are compared against the equilibrium wall-function model and Woschni’s empirical correlation.
Regularized deconvolution method for turbulent combustion modeling

Qing Wang, and Matthias Ihme

Combustion and Flame, Jan 2017

DOI
An investigation of internal flame structure in porous media combustion via X-ray Computed Tomography

Jared Dunnmon, Sadaf Sobhani, Meng Wu, Rebecca Fahrig, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2017

Publisher: Elsevier

DOI
Fuel effects on lean blow-out in a realistic gas turbine combustor

Lucas Esclapez, Peter C. Ma, Eric Mayhew, Rui Xu, Scott Stouffer, Tonghun Lee, Hai Wang, and Matthias Ihme

Combustion and Flame, Jan 2017

DOI
Non-equilibrium wall-modeling for internal combustion engine simulations with wall heat transfer

P. C. Ma, Mark Greene, Volker Sick, and Matthias Ihme

International Journal of Engine Research, Jan 2017

Publisher: SAGE Publications Sage UK: London, England

DOI
An entropy-stable hybrid scheme for simulations of transcritical real-fluid flows

Peter C Ma, Yu Lv, and Matthias Ihme

Journal of Computational Physics, Jan 2017

Publisher: Elsevier

DOI
Widom Lines in Binary Mixtures of Supercritical Fluids

Muralikrishna Raju, Daniel T Banuti, Peter C Ma, and Matthias Ihme

Scientific Reports, Jan 2017

Publisher: Nature Publishing Group

DOI
Similarity law for Widom lines and coexistence lines

Daniel T Banuti, Muralikrishna Raju, and Matthias Ihme

Physical Review E, Jan 2017

Publisher: APS

DOI
Numerical study of the ignition behavior of a post-discharge kernelin a turbulent stratified crossflow

Thomas Jaravel, Jeffrey Labahn, Brandon Sforzo, Jerry Seitzman, and Matthias Ihme

Annual Research Briefs, Jan 2017

Publisher: Center for Turbulence Research
Determining dynamic content of turbulent reacting flow LES using the Lyapunov exponent

Jeffrey W. Labahn, Gabriel Nastac, Luca Magri, and Matthias Ihme

Annual Research Briefs, Jan 2017

Publisher: Center for Turbulence Research
On the characterization of transcritical fluid states

Daniel T. Banuti, Muralikrishna Raju, and Matthias Ihme

Annual Research Briefs, Jan 2017

Publisher: Center for Turbulence Research
Structure of wall-bounded flows at transcritical conditions

Peter C. Ma, Xiang I. A. Yang, and Matthias Ihme

Annual Research Briefs, Jan 2017

Publisher: Center for Turbulence Research
Discontinuous Galerkin method for predicting heat transfer in hypersonic environments

Eric Ching, Yu Lv, and Matthias Ihme

Annual Research Briefs, Jan 2017

Publisher: Center for Turbulence Research

2016

Discontinuous Galerkin method for predicting heat transfer in hypersonic environments

Eric Ching, Yu Lv, and Matthias Ihme

Bulletin of the American Physical Society, Jan 2016

Publisher: American Physical Society
Entropy residual as a feature-based adaptation indicator for simulations of unsteady flow

Eric Ching, Yu Lv, and Matthias Ihme

In 54th AIAA Aerospace Sciences Meeting (SciTech2016), Jan 2016
Analysis of combustion closure assumptions in a dual-mode scramjet combustor

Wai Lee Chan, and Matthias Ihme

In 54th AIAA Aerospace Sciences Meeting (SciTech2016), Jan 2016
Compressible flamelet model in a rule-based turbulent combustion solver

Siddharth S. Thakur, Jeffrey Wright, and Matthias Ihme

In 54th AIAA Aerospace Sciences Meeting (SciTech2016), Jan 2016
Investigation of the mechanisms of jet-engine core noise using large-eddy simulation

Jeffrey O’Brien, Jeonglae Kim, and Matthias Ihme

In 54th AIAA Aerospace Sciences Meeting (SciTech2016), Jan 2016
High-fidelity simulations of fuel injection and atomization of a hybrid air-blast atomizer

Peter C. Ma, Lucas Esclapez, Serena Carbajal, Matthias Ihme, Timo Buschhagen, Sameer V. Naik, Jay P. Gore, and Robert P. Lucht

In 54th AIAA Aerospace Sciences Meeting (SciTech2016), Jan 2016
LES modeling of scalar transport based on high-order discontinuous finite element method: Assessment of implicit LES and scalar variance modeling

Yu Lv, and Matthias Ihme

In 46th AIAA Fluid Dynamics Conference, Jan 2016
An entropy-residual shock detector for solving conservation laws using high-order discontinuous Galerkin methods

Yu Lv, Yee Chee See, and Matthias Ihme

Journal of Computational Physics, Jan 2016

DOI
Compositional inhomogeneities as a source of indirect combustion noise

Luca Magri, Jeff O’Brien, and Matthias Ihme

Journal of Fluid Mechanics, Jan 2016

Publisher: Cambridge University Press

DOI
Group contribution method for multicomponent evaporation with application to transportation fuels

Pavan B Govindaraju, and Matthias Ihme

International Journal of Heat and Mass Transfer, Jan 2016

Publisher: Elsevier

DOI
Compliance of combustion models for turbulent reacting flow simulations

Hao Wu, and Matthias Ihme

Fuel, Jan 2016

Publisher: Elsevier

DOI
Spectral kinetic energy transfer in turbulent premixed reacting flows

Colin A. Z. Towery, Alexei Y. Poludnenko, Javier Urzay, Jeffrey O’Brien, Matthias Ihme, and Peter E. Hamlington

Physical Review E, Jan 2016

DOI
Characterizing spray flame–vortex interaction: A spray spectral diagram for extinction

Benedetta Franzelli, Aymeric Vie, and Matthias Ihme

Combustion and Flame, Jan 2016

DOI
Evaluation of subgrid dispersion models for LES of spray flames

Xinyu Zhao, Lucas Esclapez, Pavan Govindaraju, Qing Wang, and Matthias Ihme

Proceedings of the Summer Program, Jan 2016

Publisher: Center for Turbulence Research
Optimal ignition placement in diffusion flames by nonlinear adjoint looping

Ubaid A. Quadri, Luca Magri, Matthias Ihme, and Peter J. Schmidt

Proceedings of the Summer Program, Jan 2016

Publisher: Center for Turbulence Research
Inspecting Lagrangian coherent structures in turbulent combustion simulations

Vineeth Nair, Gabriel Nastac, Luca Magri, and Matthias Ihme

Proceedings of the Summer Program, Jan 2016

Publisher: Center for Turbulence Research
Including real fuel chemistry in LES of turbulent combustion

Anne Felden, Eleonore Riber, Bénédicte Cuenot, Lucas Esclapez, Matthias Ihme, and Hai Wang

Proceedings of the Summer Program, Jan 2016

Publisher: Center for Turbulence Research
Combustion noise simulation in a model gas-turbine combustor

Jeffrey O’Brien, Friedrich Bake, and Matthias Ihme

Proceedings of the Summer Program, Jan 2016

Publisher: Center for Turbulence Research
Assessment of high-order DG methods for LES of compressible flows

Koen Hillewaert, Jean-Sébastien Cognone, Scott M. Murman, Yu Lv, and Matthias Ihme

Proceedings of the Summer Program, Jan 2016

Publisher: Center for Turbulence Research
Toward direct numerical simulation of multicomponent fuel spray auto-ignition

Lucas Esclapez, Pavan Govindaraju, and Matthias Ihme

Annual Research Briefs, Jan 2016

Publisher: Center for Turbulence Research
Supercritical pseudoboiling for general fluids and its application to injection

Daniel T. Banuti, Muralikrishna Raju, and Matthias Ihme

Annual Research Briefs, Jan 2016

Publisher: Center for Turbulence Research
Numerical methods to prevent pressure oscillations in transcritical flows

Peter C. Ma, Yu Lv, and Matthias Ihme

Annual Research Briefs, Jan 2016

Publisher: Center for Turbulence Research
Compositional inhomogeneities as a source of indirect noise in subsonic and supersonic nozzles

Luca Magri, Jeffrey O’Brien, and Matthias Ihme

Annual Research Briefs, Jan 2016

Publisher: Center for Turbulence Research
Entropy residual shock detector for shock-capturing using high-order discontinuous Galerkin scheme

Yu Lv, and Matthias Ihme

Annual Research Briefs, Jan 2016

Publisher: Center for Turbulence Research

2015

Mild ignition phenomena in rapid compression machines

Kevin Grogan, S. Scott Goldsborough, and Matthias Ihme

In Proceedings of the 25th International Colloquium on the Dynamics of Explosions and Reactive Systems, Jan 2015
Modeling of Wall Heat Transfer and Flame/Wall Interaction - A Flamelet Model with Heat-Loss Effects

Hao Wu, and Matthias Ihme

In 9th U. S. National Combustion Meeting, Jan 2015
Multicomponent Droplet Evaporation Using Group Contribution Method with Application to Fuel Blends

Pavan B. Govindaraju, Qing Wang, and Matthias Ihme

In 9th U. S. National Combustion Meeting, Jan 2015
Modeling Gas Dynamic Effects in Shock-Tubes for Reaction Kinetics Measurements

Kevin Grogan, Qing Wang, and Matthias Ihme

In 53rd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2015
A General and Robust High-Order Numerical Framework for Shock-Capturing: Entropy-Bounding, Shock Detection and Artificial Viscosity

Yu Lv, Yee Chee See, and Matthias Ihme

In 53rd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2015
Linear Analysis of Jet-Engine Core Noise Based upon High-Fidelity Combustor and Turbine Simulations

Jeffrey D. O’Brien, Jeonglae Kim, and Matthias Ihme

In 53rd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2015
A Fidelity Adaptive Modeling Framework for Combustion Systems Based on Model Trust-Region

Hao Wu, Yee Chee See, Qing Wang, and Matthias Ihme

In 53rd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2015
Linear Analysis of Engine Core Noise Using a Hybrid Modeling Approach

Jeffrey D. O’Brien, Jeonglae Kim, and Matthias Ihme

In 21st AIAA/CEAS Aeroacoustics Conference, Jan 2015
On the generalisation of the mixture fraction to a monotonic mixing-describing variable for the flamelet formulation of spray flames

Benedetta Franzelli, Aymeric Vie, and Matthias Ihme

Combustion Theory and Modelling, Jan 2015

DOI
Characterization of scalar mixing in dense gaseous jets using X-ray computed tomography

Jared Dunnmon, Sadaf Sobhani, Tao Wook Kim, Anthony Kovscek, and Matthias Ihme

Experiments in Fluids, Jan 2015

DOI
An SMLD joint PDF model for turbulent non-premixed combustion using the flamelet progress-variable approach

Alessandro Coclite, Giuseppe Pascazio, Pietro De Palma, Luigi Cutrone, and Matthias Ihme

Flow, Turbulence and Combustion, Jan 2015

DOI
Analysis of segregation and bifurcation in turbulent spray flames: A 3D counterflow configuration

Aymeric Vié, Benedetta Franzelli, Yang Gao, Tianfeng Lu, Hai Wang, and Matthias Ihme

Proceedings of the Combustion Institute, Jul 2015

DOI
Large eddy simulation of a partially-premixed gas turbine model combustor

Yee Chee See, and Matthias Ihme

Proceedings of the Combustion Institute, Sep 2015

Publisher: The Combustion Institute

DOI
Computational analysis of re-ignition and re-initiation mechanisms of quenched detonation waves behind a backward facing step

Yu Lv, and Matthias Ihme

Proceedings of the Combustion Institute, Aug 2015

DOI
Coupling of flame geometry and combustion instabilities based on kilohertz formaldehyde PLIF measurements

Patton M. Allison, Yuntao Chen, Matthias Ihme, and James F. Driscoll

Proceedings of the Combustion Institute, Jul 2015

Publisher: The Combustion Institute

DOI
Quantitative model-based imaging of mid-infrared radiation from a turbulent nonpremixed jet flame and plume

Brent A. Rankin, Matthias Ihme, and Jay P. Gore

Combustion and Flame, Jul 2015

DOI
An SMLD joint PDF model for turbulent non-premixed combustion using the flamelet progress-variable approach

Alessandro Coclite, Giuseppe Pascazio, Pietro De Palma, Luigi Cutrone, and Matthias Ihme

Flow, Turbulence and Combustion, Jul 2015

DOI
Entropy-bounded discontinuous Galerkin scheme for Euler equations

Yu Lv, and Matthias Ihme

Journal of Computational Physics, Jul 2015

DOI
Ignition regimes in rapid compression machines

Kevin P. Grogan, S. Scott Goldsborough, and Matthias Ihme

Combustion and Flame, Jul 2015

DOI
A multi-scale asymptotic scaling and regime analysis of flamelet equations including tangential diffusion effects for laminar and turbulent flames

Arne Scholtissek, Wai Lee Chan, Hongbin Xu, Franziska Hunger, Hemanth Kolla, Jacqueline H. Chen, Matthias Ihme, and Christian Hasse

Combustion and Flame, Jul 2015

Abs DOI

Abstract Recently, the relevance of tangential diffusion effects has been identified for laminar flames. These effects are not considered in the classical flamelet equations. In the present work, flamelet equations including these effects are derived, and their relevance is investigated by a multi-scale asymptotic scaling analysis. The analysis yields characteristic ratios dependent on the local curvature of the mixture fraction field, the scalar dissipation rate, and the flame thickness, which indicate whether tangential diffusion effects become important. By comparing relevant scales, a regime diagram is developed and three different flamelet regimes are identified. In regime I, the classical flamelet equations are valid. In regime II, differential diffusion of species and temperature in flame-tangential direction becomes relevant. In regime III, additional transport along mixture fraction isosurfaces exhibits an influence on the flame structure. In the latter case it is not sufficient to condition species mass fractions and temperature on the mixture fraction alone since these quantities are not represented by a one-dimensional structure. The asymptotic scaling is verified against fully resolved numerical data of a laminar non-premixed methane–air flame and a turbulent lifted hydrogen jet flame. Budgets of different flamelet solutions of the laminar flame reveal that tangential diffusion effects are dominant over the classical flamelet terms near the flame centerline, while in regions away from it, standard flamelet terms are prevailing. For the turbulent flame, the results show that tangential diffusion effects are more localized and can exceed flame-normal transport, although, unsteadiness is more likely the key factor of the configuration. While the classical flamelet model is applicable for certain flames, this study shows that tangential diffusion effects may require consideration for general flame configurations.
Weak and strong ignition of hydrogen/oxygen mixtures in shock-tube systems

Kevin P. Grogan, and Matthias Ihme

Proceedings of the Combustion Institute, Sep 2015

Publisher: The Combustion Institute

DOI
A Pareto-efficient combustion framework with submodel assignment for predicting complex flame configurations

Hao Wu, Yee Chee See, Qing Wang, and Matthias Ihme

Combustion and Flame, Sep 2015

DOI
Regularized deconvolution method for turbulent combustion modeling

Qing Wang, Hao Wu, and Matthias Ihme

Annual Research Briefs, Sep 2015

Publisher: Center for Turbulence Research
Recent advances in linear methods for sensitivity, passive control and modeling of thermo-acoustic instabilities

Luca Magri, and Matthias Ihme

Annual Research Briefs, Sep 2015

Publisher: Center for Turbulence Research
Large-eddy simulation of fuel effect on lean blow-out in gas turbines

Lucas Esclapez, Peter C. Ma, and Matthias Ihme

Annual Research Briefs, Sep 2015

Publisher: Center for Turbulence Research
Large-eddy simulations and turbulent combustion model analysis of a dual-mode scramjet combustor

Wai Lee Chan, and Matthias Ihme

Annual Research Briefs, Sep 2015

Publisher: Center for Turbulence Research
Discontinuous Galerkin scheme for turbulent flow simulations

Peter C. Ma, Yu Lv, and Matthias Ihme

Annual Research Briefs, Sep 2015

Publisher: Center for Turbulence Research

2014

Characterizing the Regimes of Spray Flame-Vortex Interactions: A Spray Spectral Diagram for Extinction and Re-Ignition

Benedetta Franzelli, Aymeric Vie, and Matthias Ihme

In ILASS-Europe 2014, 26th Annual Conference on Liquid Atomization and Spray Systems, Sep 2014
Large Eddy Simulation of Supercritical Mixing and Combustion for Rocket Applications

Jean-Pierre Hickey, and Matthias Ihme

In 52nd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Sep 2014
LES Investigation of Flow Field Sensitivity in a Gas Turbine Model Combustor

Yee Chee See, and Matthias Ihme

In 52nd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Sep 2014
Large-Eddy Simulations of a Dual-Mode Scramjet Combustor: Operating Point "A" of University of Virginia’s Scramjet Experiments

Wai Lee Chan, and Matthias Ihme

In 52nd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Sep 2014
Numerical Investigation of Detonation Transmission Mechanism based on High-order Discontinuous Galerkin Scheme

Yu Lv, and Matthias Ihme

In 52nd AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Sep 2014
Modeling of non-equilibrium homogeneous turbulence in rapidly compressed flows

Peter E. Hamlington, and Matthias Ihme

Flow, Turbulence and Combustion, Jun 2014

DOI
Tabulated chemistry approach for diluted combustion regimes with internal recirculation and heat losses

Jean Lamouroux, Matthias Ihme, Benoit Fiorina, and Olivier Gicquel

Combustion and Flame, Mar 2014

Publisher: The Combustion Institute.

DOI
Discontinuous Galerkin method for multicomponent chemically reacting flows and combustion

Yu Lv, and Matthias Ihme

Journal of Computational Physics, Aug 2014

DOI
Subgrid-scale backscatter in reacting and inert supersonic hydrogen–air turbulent mixing layers

Jeffrey O’Brien, Javier Urzay, Matthias Ihme, Parviz Moin, and A. Saghafian

Journal of Fluid Mechanics, Mar 2014

DOI
Effects of finite-rate chemistry and detailed transport on the instability of jet diffusion flames

Yee Chee See, and Matthias Ihme

Journal of Fluid Mechanics, Mar 2014

DOI
Effects of flow-field and mixture inhomogeneities on the ignition dynamics in continuous flow reactors

Hao Wu, and Matthias Ihme

Combustion and Flame, Mar 2014

Publisher: The Combustion Institute.

DOI
Assessment of model assumptions and budget terms of the unsteady flamelet equations for a turbulent reacting jet-in-cross-flow

Wai Lee Chan, Hemanth Kolla, Jacqueline H. Chen, and Matthias Ihme

Combustion and Flame, Oct 2014

Publisher: The Combustion Institute.

DOI
Instability of elliptic liquid jets: Temporal linear stability theory and experimental analysis

Ghobad Amini, Yu Lv, Ali Dolatabadi, and Matthias Ihme

Physics of Fluids, Oct 2014

DOI
Taming nonlinear instability for discontinuous Galerkin scheme with artificial viscosity

Yu Lv, and Matthias Ihme

Annual Research Briefs, Oct 2014

Publisher: Center for Turbulence Research
Accounting for strain-rate effect in soot modeling of turbulent flames

Benedetta Franzelli, Alberto Cuoci, Alessandro Stagni, Chiara Saggese, Alessio Frassoldati, Tiziano Faravelli, and Matthias Ihme

Annual Research Briefs, Oct 2014

Publisher: Center for Turbulence Research
Linear analysis of engine core noise using a hybrid modeling approach

Jeonglae Kim, Jeffrey O’Brien, and Matthias Ihme

Annual Research Briefs, Oct 2014

Publisher: Center for Turbulence Research
An adaptive combustion framework

Yee Chee See, Hao Wu, QING Wang, and Matthias Ihme

Annual Research Briefs, Oct 2014

Publisher: Center for Turbulence Research
Characterizing the regimes of spray flame-vortex interactions: A spray spectral diagram for extinction

Benedetta Franzelli, Aymeric Vie, and Matthias Ihme

Annual Research Briefs, Oct 2014

Publisher: Center for Turbulence Research
A spray-flamelet formulation using an effective composition-space variable

Benedetta Franzelli, Aymeric Vie, and Matthias Ihme

Annual Research Briefs, Oct 2014

Publisher: Center for Turbulence Research
Supercritical and transcritical real-fluid mixing in diesel engine applications

Peter C. Ma, Luis Bravo, and Matthias Ihme

In Proceedings of the Summer Program, Oct 2014
Counter-gradient subgrid-scale transport and energy backscatter in turbulent deflagrations

Jeffrey O’Brien, Javier Urzay, Alexei Y. Poludnenko, Peter E. Hamlington, and Matthias Ihme

In Proceedings of the Summer Program, Oct 2014
Spectral energy dynamics in premixed flames

Colin A. Z. Towery, Alexei Y. Poludnenko, Javier Urzay, Matthias Ihme, and Peter E. Hamlington

In Proceedings of the Summer Program, Oct 2014
Towards concurrent identification of flame dynamics and combustion noise of enclosed flames

Camilo F. Silva, Wolfgang Polifke, Jeffrey O’Brien, and Matthias Ihme

In Proceedings of the Summer Program, Oct 2014
Multiple-scale adjoint sensitivity analysis of hydrodynamic/thermo-acoustic instability in turbulent combustion chambers

Luca Magri, Yee Chee See, Matthias Ihme, and Matthew P. Juniper

In Proceedings of the Summer Program, Oct 2014

2013

Parallel Compressible Solver for Unsteady Turbulent Combustion in Rocket Injectors Using Flamelet Models

Siddharth S. Thakur, Jeffrey Wright, and Matthias Ihme

In 21st AIAA Computational Fluid Dynamics Conference, Jun 2013

DOI
Discontinuous Galerkin Method for Compressible Viscous Reacting Flow

Yu Lv, and Matthias Ihme

In 21st AIAA Computational Fluid Dynamics Conference, Jun 2013

DOI
Large Eddy Simulation of Shear Coaxial Rocket Injector: Real Fluid Effects

Jean-Pierre Hickey, Peter C. Ma, Matthias Ihme, and Siddharth S. Thakur

In 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Jul 2013

DOI
Liquid Jet Instability Under Gravity Effects

Ghobad Amini, and Matthias Ihme

In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2013

Issue: January

DOI
Large-Eddy Simulation of a Gas Turbine Model Combustor

Yee Chee See, and Matthias Ihme

In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2013

Issue: January

DOI
Development of Discontinuous Galerkin Method for Detonation and Supersonic Combustion

Yu Lv, and Matthias Ihme

In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2013

Issue: January

DOI
Detailed Simulations of Shock-Bifurcation and Ignition of an Argon-diluted Hydrogen/Oxygen Mixture in a Shock Tube

Matthias Ihme, Yong Sun, and Ralf Deiterding

In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition,, Jan 2013

Issue: January
Large-eddy simulation of a piloted premixed jet burner

Yuntao Chen, and Matthias Ihme

Combustion and Flame, Dec 2013

Publisher: The Combustion Institute.

DOI
Acoustic characterization of a partially-premixed gas turbine model combustor: Syngas and hydrocarbon fuel comparisons

Patton M Allison, James F. Driscoll, and Matthias Ihme

Proceedings of the Combustion Institute, Jan 2013

DOI
Effect of gravity on capillary instability of liquid jets

Ghobad Amini, Matthias Ihme, and Ali Dolatabadi

Physical Review E, May 2013

DOI
Supercritical mixing and combustion in rocket propulsion

Jean-Pierre Hickey, and Matthias Ihme

Annual Research Briefs, May 2013

Publisher: Center for Turbulence Research
On the description of the spray flame structure in a mixture fraction space

Aymeric Vie, Benedetta Franzelli, Benoit Fiorina, Nasser Darabiha, and Matthias Ihme

Annual Research Briefs, May 2013

Publisher: Center for Turbulence Research
Backscatter of turbulent kinetic energy in chemically-reacting compressible flows

Javier Urzay, Jeffrey O’Brien, Matthias Ihme, Parviz Moin, and Amirreza Saghafian

Annual Research Briefs, May 2013

Publisher: Center for Turbulence Research
Study of thermal boundary layer in pulsatile flows

Damien Kah, Tim Ewan, and Matthias Ihme

Annual Research Briefs, May 2013

Publisher: Center for Turbulence Research

2012

Jet noise receptivity analysis of perfectly expanded supersonic jet flows

Yee Chee See, Ghobad Amini, Chris Koh, and Matthias Ihme

In 18th AIAA/CEAS Aeroacoustics Conference, May 2012
Analysis of a jet in cross flow using an unsteady flamlet model

Wai Lee Chan, Hemanth Kolla, Matthias Ihme, and Jacqueline H. Chen

In 2012 Spring Meeting of Central States Section of the Combustion Institute, May 2012
Flame characterization of a piloted premixed jet burner

Yuntao Chen, and Matthias Ihme

In 2012 Spring Meeting of Central States Section of the Combustion Institute, May 2012
Characterization of turbulent transition and shock/boundary layer interaction in shock tubes

Yong Sun, Matthias Ihme, and Ralf Deiterding

In 23rd International Congress of Theoretical and Applied Mechanics (ICTAM 2012), May 2012
Modeling of a piloted jet burner using large-eddy simulation

Yuntao Chen, and Matthias Ihme

In 23rd International Congress of Theoretical and Applied Mechanics (ICTAM 2012), May 2012
Linear Stability Analysis of a Non-premixed Buoyant Jet Flame

Yee Chee See, and Matthias Ihme

In 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2012

Issue: January

DOI
Acoustic Behavior of a Partially-Premixed Gas Turbine Model Combustor

Patton Allison, James Driscoll, and Matthias Ihme

In 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2012

Issue: January

DOI
Characterization of Mixing and Ignition Effects in Flow-Reactor Facilities Using a Particle Method

Simon Weiher, and Matthias Ihme

In 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2012

Issue: January

DOI
Large-Eddy Simulation of a Jet-in-Hot-Coflow Burner Operating in the Oxygen-Diluted Combustion Regime

Matthias Ihme, Jian Zhang, Guowei He, and Bassam Dally

Flow, Turbulence and Combustion, May 2012

DOI
On the role of turbulence and compositional fluctuations in rapid compression machines: Autoignition of syngas mixtures

Matthias Ihme

Combustion and Flame, Apr 2012

DOI
Regularization of reaction progress variable for application to flamelet-based combustion models

Matthias Ihme, Lee Shunn, and Jian Zhang

Journal of Computational Physics, Oct 2012

DOI
On the generation of direct combustion noise in turbulent non-premixed flames

Matthias Ihme, and Heinz Pitsch

International Journal of Aeroacoustics, Mar 2012

DOI
Budget analysis and model-assessment of the flamelet-formulation: Application to a reacting jet-in-cross-flow

Wai Lee Chan, Yee Chee See, Matthias Ihme, Hemanth Kolla, and Jacqueline H. Chen

In Proceedings of the Summer Program, Mar 2012

2011

Characterization of Flow Field Structure and Species Composition in a Shear Coaxial Rocket GH2/GO2 Injector: Modeling of Wall Heat Losses

D. Lee, S. Thakur, J. Wright, Matthias. Ihme, and W. Shyy

In 47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, Jul 2011

Issue: August

DOI
Reconcile Discrepancies of Current Syngas Kinetics Models by Considering Turbulence Effects on Ignition Delay at Gas-Turbine Relevant Operating Conditions

Matthias Ihme

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Jan 2011

ISBN: 978-1-60086-950-1 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI
LES flamelet modeling of a three-stream MILD combustor: Analysis of flame sensitivity to scalar inflow conditions

Matthias Ihme, and Yee Chee See

Proceedings of the Combustion Institute, Jan 2011

Publisher: Elsevier Inc.

DOI
Reduced-Order Modeling of Turbulent Reacting Flows with Application to Ramjets and Scramjets

Sean M. Torrez, James F. Driscoll, Matthias Ihme, and Matthew L. Fotia

Journal of Propulsion and Power, Mar 2011

DOI

2010

Characterization and Sensitivity Analysis of a Turbulent Diffusion Flame in Diluted Hot Coflow

Yee Chee See, and Matthias Ihme

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Jan 2010

ISBN: 978-1-60086-959-4 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI
Turbulence-Chemistry Interaction and Heat Transfer Modeling of H2/O2 Gaseous Injector Flows

Emre Sozer, Ezeldin Hassan, Seokjun Yun, Siddharth Thakur, Jeffrey Wright, Matthias Ihme, and Wei Shyy

In 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Jan 2010

Issue: January

DOI
LES modeling of kinetics-controlled combustion regimes: Autoignition

Matthias Ihme, and Yee Chee See

In Fifth European Conference on Computational Fluid Dynamics, ECCOMAS CFD, Jan 2010
Prediction of autoignition in a lifted methane/air flame using an unsteady flamelet/progress variable model

Matthias Ihme, and Yee Chee See

Combustion and Flame, Oct 2010

DOI

2009

Large-Eddy Simulation of a Turbulent Lifted Flame in a Vitiated Co-Flow

Matthias Ihme, and Yee Chee See

47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, Jan 2009

ISBN: 978-1-60086-973-0 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI
Prediction of autoignition in a lifted methane/air flame using an unsteady flamelet/progress variable model

Yee Chee See, and Matthias Ihme

In Sixth U.S. National Combustion Meeting, Jan 2009
Radiation of noise in turbulent non-premixed flames

Matthias Ihme, Heinz Pitsch, and Daniel Bodony

Proceedings of the Combustion Institute, Jan 2009

DOI
Optimal artificial neural networks and tabulation methods for chemistry representation in LES of a bluff-body swirl-stabilized flame

Matthias Ihme, Christoph Schmitt, and Heinz Pitsch

Proceedings of the Combustion Institute, Jan 2009

DOI
Analysis of different sound source formulations to simulate combustion generated noise using a hybrid LES/APE-RF method

Thanh Bui, Matthias Ihme, Wolfgang Schröder, and Heinz Pitsch

International Journal of Aeroacoustics, Jan 2009

DOI

2008

Numerical Applicability of Different Sound Source Formulations to Compute Combustion Noise Using Acoustic Perturbation Equations for Reacting Flows

Thanh Bui, Matthias Ihme, Matthias Meinke, Wolfgang Schroeder, and Heinz Pitsch

14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference), May 2008

ISBN: 978-1-60086-983-9 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI
Large-Eddy Simulation of Turbulent Reacting Flows

Heinz Pitsch, Olivier Desjardins, Guillaume Balarac, and Matthias Ihme

In 46th AIAA Aerospace Sciences Meeting and Exhibit, May 2008
Prediction of extinction and reignition in nonpremixed turbulent flames using a flamelet/progress variable model: 1. A priori study and presumed PDF closure

Matthias Ihme, and Heinz Pitsch

Combustion and Flame, Oct 2008

DOI
Prediction of extinction and reignition in nonpremixed turbulent flames using a flamelet/progress variable model: 2. Application in LES of Sandia flames D and E

Matthias Ihme, and Heinz Pitsch

Combustion and Flame, Oct 2008

DOI
Generation of optimal artificial neural networks using a pattern search algorithm: application to approximation of chemical systems.

Matthias Ihme, Alison L Marsden, and Heinz Pitsch

Neural Computation, Feb 2008

Abs DOI

A pattern search optimization method is applied to the generation of optimal artificial neural networks (ANNs). Optimization is performed using a mixed variable extension to the generalized pattern search method. This method offers the advantage that categorical variables, such as neural transfer functions and nodal connectivities, can be used as parameters in optimization. When used together with a surrogate, the resulting algorithm is highly efficient for expensive objective functions. Results demonstrate the effectiveness of this method in optimizing an ANN for the number of neurons, the type of transfer function, and the connectivity among neurons. The optimization method is applied to a chemistry approximation of practical relevance. In this application, temperature and a chemical source term are approximated as functions of two independent parameters using optimal ANNs. Comparison of the performance of optimal ANNs with conventional tabulation methods demonstrates equivalent accuracy by considerable savings in memory storage. The architecture of the optimal ANN for the approximation of the chemical source term consists of a fully connected feedforward network having four nonlinear hidden layers and 117 synaptic weights. An equivalent representation of the chemical source term using tabulation techniques would require a 500 x 500 grid point discretization of the parameter space.
Large-eddy simulation of turbulent reacting flows

Heinz Pitsch, Olivier Desjardins, Guillaume Balarac, and Matthias Ihme

Progress in Aerospace Sciences, Aug 2008

DOI
Modeling of radiation and nitric oxide formation in turbulent nonpremixed flames using a flamelet/progress variable formulation

Matthias Ihme, and Heinz Pitsch

Physics of Fluids, Aug 2008

DOI

2007

Enhanced Hybrid LES/CAA Approach for Combustion-Induced Noise in Complex Geometries

Manfred Kaltenbacher, Matthias Ihme, and Heinz Pitsch

13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference), May 2007

ISBN: 978-1-62410-003-1 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI

2006

Prediction of Combustion-Generated Noise in Non-Premixed Turbulent Jet Flames Using LES

Matthias Ihme, Daniel Bodony, and Heinz Pitsch

12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference), May 2006

ISBN: 978-1-62410-021-5 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI
Numerical simulation of flow- and combustion-induced sound using a hybrid LES/CAA approach

Matthias Ihme, Manfred Kaltenbacher, and Heinz Pitsch

Proceedings of the Summer Program, May 2006

Publisher: Center for Turbulence Research
On the optimization of artificial neural networks for application to the approximation of chemical systems

Matthias Ihme, Alison L. Marsden, and Heinz Pitsch

Annual Research Briefs, May 2006

Publisher: Center for Turbulence Research
Modeling of high-pressure mixing and combustion in liquid rocket injectors

Luigi Cutrone, Matthias Ihme, and Marcus Herrmann

In Proceedings of the Summer Program, May 2006

2005

LES of a Non-Premixed Flame Using an Extended Flamelet/Progress Variable Model

Matthias Ihme, and Heinz Pitsch

43rd AIAA Aerospace Sciences Meeting and Exhibit, Jan 2005

ISBN: 978-1-62410-064-2 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI
An Unsteady/Flamelet Progress Variable Method for LES of Nonpremixed Turbulent Combustion

Heinz Pitsch, and Matthias Ihme

43rd AIAA Aerospace Sciences Meeting and Exhibit, Jan 2005

ISBN: 978-1-62410-064-2 Place: Reston, Virigina Publisher: American Institute of Aeronautics and Astronautics

DOI
Prediction of local extinction and re-ignition effects in non-premixed turbulent combustion using a flamelet/progress variable approach

Matthias Ihme, Chong M. Cha, and Heinz Pitsch

Proceedings of the Combustion Institute, Jan 2005

Publisher: The Combustion Institute

DOI
Stochastic mixing model with power law decay of variance

Sergei Fedotov, Matthias Ihme, and Heinz Pitsch

Physical Review E, Jan 2005

DOI
Towards the prediction of combustion-generated noise in non-premixed turbulent flames using large-eddy simulation

Matthias Ihme, Daniel J. Bodony, and Heinz Pitsch

Annual Research Briefs, Jan 2005

Publisher: Center for Turbulence Research

2003

A priori study of a flamelet/progress variable approach for non-premixed turbulent combustion

Matthias Ihme, Charles D. Pierce, Chong M. Cha, and Heinz Pitsch

In Third Joint Meeting of the U.S. Section of the Combustion Institute, Jan 2003
Stochastic mixing model with power law decay of variance

Sergei Fedotov, Matthias Ihme, and Heinz Pitsch

Annual Research Briefs, Jan 2003

Publisher: Center for Turbulence Research

2002

Sound prediction for a turbulent co-flowing jet based on LES

Matthias Ihme, and Michael Breuer

In International Workshop on LES for Acoustics, Jan 2002