Lagrangian Large Eddy Simulations via Physics Informed Machine Learning
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Abstract: High Reynolds Homogeneous Isotropic Turbulence (HIT) is fully described within the Navier-Stocks (NS) equations, which are notoriously difficult to solve numerically. Engineers, interested primarily in understanding turbulence at reduced but the sufficiently large range of resolved scales, have designed heuristics, known under the name of Large Eddy Simulation (LES). The standard LES is described in terms of evolving in time Eulerian velocity field defined over the points of a spatial grid with the mean-spacing correspondent to the resolved scale. This classic Eulerian LES depends on assumptions about the effects of sub-grid scales on the resolved scales.
In this talk, based on UArizona – Los Alamos collaboration co-lead by the speaker, Dr. Chertkov presents an alternative approach stated in terms of Lagrangian particles moving with the turbulent flow. His newly designed Lagrangian LES, thus L-LES, is described by equations that generalize the weakly compressible Smooth Particle Hydrodynamics formulation with extended parametric and functional freedom which is then resolved/fixed via Machine Learning training on Lagrangian data from a Direct Numerical Simulation of the NS equations.
Bio: Michael (Misha) Chertkov is a professor of mathematics and chair of the Graduate Interdisciplinary Program in Applied Mathematics at the University of Arizona since 2019. His research focuses on the foundational problems in mathematics and statistics applied to physical systems, in particular fluid mechanics, to engineered systems such as energy grids, and to some bio-social systems. Dr. Chertkov received his Ph.D. in physics from the Weizmann Institute of Science in 1996, spent three years at Princeton University as an R.H. Dicke Fellow in the Department of Physics, and joined Los Alamos National Laboratory in 1999, initially as a J.R. Oppenheimer Fellow and then as a Technical Staff Member in Theory Division. He has published more than 250 papers, is a fellow of the AAAS, a fellow of the American Physical Society and a senior member of IEEE.
Place: AME Lecture Hall, Room S212 or Zoom link