TY - JOUR
T1 - Multifidelity validation of digital surrogates using variable-density turbulent mixing models
AU - Musci, Benjamin
AU - Olson, Britton
AU - Petter, Samuel
AU - Pathikonda, Gokul
AU - Ranjan, Devesh
N1 - Funding Information:
The authors thank Dr. Brandon Morgan for his consultation on using RANSbox and for his invaluable insight concerning the interpretation of RANS results. Thanks are also in order for Erin Wilson regarding her immense contributions to the aesthetic of plots and figures in this article. The authors also thank Ben's van, which facilitated much of this work. The first author is also incredibly thankful for the funding and opportunities provided by the DOE NNSA Stewardship Science Graduate Fellowship (SSGF) and the LLNL Defense Science and Technology Fellowship (DSTI). In addition, we acknowledge support from the DOE Early Career Award and Office of Fusion Energy Science in the form of Grant No. DE-SC0016181. Finally, this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.
Publisher Copyright:
© 2023 American Physical Society.
PY - 2023/1
Y1 - 2023/1
N2 - In this study, ensembles of experimental data are presented and utilized to compare and validate two models used in the simulation of variable-density (Atwood = 0.22), compressible turbulent mixing. Though models of this kind (Reynolds averaged Navier-Stokes and large-eddy simulations) have been validated extensively with more canonical flows in previous studies, the present approach offers novelty in the complexity of the geometry, the ensemble-based validation, and the uniformity of the computational framework on which the models are tested. Moreover, all experimental and computational tasks were completed by the authors which has led to a tightly coupled experimental configuration with its "digital twin."The experimental divergent-shock-tube facility and its data acquisition methods are described and replicated in simulation space. A 2D Euler model which neglects the turbulent mixing at the interface is optimized to experimental data using a Gaussian process. This model then serves as the basis for both the 2D RANS and 3D LES studies that make comparisons to the mixing-layer data from the experiment. A relatively simple RANS model is shown to produce good agreement with experimental data only at late flow development times. The LES ensembles generally show good agreement with experimental data but display sensitivity to the characterization of initial conditions. Resolution-dependent behavior is also observed for certain higher-order statistics of interest. Overall, the LES model successfully captures the effects of divergent geometry, compressibility, and combined nonlinear instabilities inherent to the problem. The successful prediction of mixing width and its growth rate highlight the existence of three distinct regimes in the development of the instability, each with similarities to previously studied instabilities.
AB - In this study, ensembles of experimental data are presented and utilized to compare and validate two models used in the simulation of variable-density (Atwood = 0.22), compressible turbulent mixing. Though models of this kind (Reynolds averaged Navier-Stokes and large-eddy simulations) have been validated extensively with more canonical flows in previous studies, the present approach offers novelty in the complexity of the geometry, the ensemble-based validation, and the uniformity of the computational framework on which the models are tested. Moreover, all experimental and computational tasks were completed by the authors which has led to a tightly coupled experimental configuration with its "digital twin."The experimental divergent-shock-tube facility and its data acquisition methods are described and replicated in simulation space. A 2D Euler model which neglects the turbulent mixing at the interface is optimized to experimental data using a Gaussian process. This model then serves as the basis for both the 2D RANS and 3D LES studies that make comparisons to the mixing-layer data from the experiment. A relatively simple RANS model is shown to produce good agreement with experimental data only at late flow development times. The LES ensembles generally show good agreement with experimental data but display sensitivity to the characterization of initial conditions. Resolution-dependent behavior is also observed for certain higher-order statistics of interest. Overall, the LES model successfully captures the effects of divergent geometry, compressibility, and combined nonlinear instabilities inherent to the problem. The successful prediction of mixing width and its growth rate highlight the existence of three distinct regimes in the development of the instability, each with similarities to previously studied instabilities.
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U2 - 10.1103/PhysRevFluids.8.014501
DO - 10.1103/PhysRevFluids.8.014501
M3 - Article
AN - SCOPUS:85146307921
SN - 2469-990X
VL - 8
JO - Physical Review Fluids
JF - Physical Review Fluids
IS - 1
M1 - 014501
ER -