Woodruff School of Mechanical Engineering
Reynolds-Averaged Modeling of Rayleigh Taylor Turbulent Mixing: Progress and Challenges
Dr. Oleg Schilling
Lawrence Livermore National Laboratory
Friday, November 16, 2018 at 2:00:00 PM
Love Building, Room 210
Dr. Devesh Ranjan
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−E 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−L-a 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−E 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.
Oleg Schilling is a Staff Theoretical, Computational and Applied Physicist at the Lawrence Livermore National Laboratory (LLNL). He received his B.A., M.A., M.Phil., and Ph.D. degrees in Physics from Columbia University in New York in 1987, 1988, 1990, and 1994, respectively. He expanded his formal training in theoretical physics to include fluid dynamics, turbulence, astrophysics, and computational physics, and conducted doctoral research jointly between the Physics Department at Columbia and the NASA Goddard Institute of Space Studies. He joined LLNL in 1994 as a Post-Doctoral Fellow and began research on compressible turbulent mixing in 1995. He became a staff physicist in 1996 to conduct theory, modeling, and numerical simulation of turbulent mixing induced by Rayleigh–Taylor and Richtmyer–Meshkov instabilities, with an emphasis on the integration of modeling, simulation, and experiment. He has collaborated with students and faculty at many universities on turbulent mixing, has given numerous presentations at national and international conferences, and has published articles on various topics in turbulence. He chaired the 8th and 14th International Workshop on the Physics of Compressible Turbulent Mixing in 2001 and 2014. In 2004 he was appointed as an Adjunct Member of the Graduate Faculty in the Dwight Look College of Engineering at Texas A & M University. He was an invited lecturer at the First and Second International Conference on Advanced Computing and Simulation: The Physics and Computation of Rayleigh-Taylor and Richtmyer-Meshkov Instabilities at the University of Cambridge in 2005 and 2007. He served two terms on the Editorial Board of Physical Review E in the Fluid Mechanics and Turbulence topical areas from 2005 to 2010, and was appointed as an Associate Editor of the ASME Journal of Fluids Engineering in 2014. He has also served on numerous review panels at LLNL, Los Alamos National Laboratory, and other agencies.
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