Berkeley Fluids Seminar

Reynolds-Averaged Modeling of Rayleigh‒Taylor Turbulent Mixing: Progress and Challenges

Monday, February 25, 2019

12:00-13:00, 3110 Etcheverry Hall

Oleg Schilling

(Lawrence Livermore National Laboratory)

Abstract: Recent progress and challenges in modeling Rayleigh−Taylor instability-induced turbulent mixing using Reynolds-averaged turbulence models are reviewed. This includes efforts to use an advanced, multicomponent K−ε model that incorporates terms generally neglected in other models, as well as comparisons of predictions of this model with those from the K−L−a model. Applications of these models to a variety of Rayleigh−Taylor unstable, as well as stable, cases with different Atwood numbers are presented and discussed. It is shown that the predictions of the K−ε model are consistent with results from implicit large-eddy simulations (ILES) of miscible mixing, and that the predictions of the K−L−a model are consistent with immiscible mixing. For Rayleigh−Taylor flows with stable phases, it is shown that the K−ε model predicts trends in agreement with simulation and experimental data. Some of the important challenges facing the Reynolds-averaged modeling approach are also briefly discussed, including model calibration to data, and ambiguities in the choice of initial conditions.

(This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.)

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Acknowledgments

Prof. Eliot Quataert on behalf of The Theoretical Astrophysics Center and the Astronomy Department (UC Berkeley)

Prof. Philip S. Marcus on behalf of the Mechanical Engineering Department (UC Berkeley)

Prof. Michael Manga (Earth and Planetary Science, UC Berkeley)

Prof. Evan Variano (Civil and Environmental Engineering, UC Berkeley)