Dynamic Bridging Paradigm for Coarse Grained Simulations of Turbulent Material Mixing.

We focus on simulating the consequences of material interpenetration, hydrodynamical instabilities, and mixing arising from perturbations at shocked material interfaces, as vorticity is introduced by the impulsive loading of shock waves -- e.g., as in inertial confinement fusion capsule implosions. Such complex flow physics is capturable with Coarse Grained Simulation -- classical and implicit Large-Eddy Simulation, where the small-scale flow dynamics is presumed enslaved to the dynamics of the largest scales. Beyond shocks and variable-density turbulence multiscale-resolution issues, we must address the difficult problem of predicting flow transitions promoted by energy deposited at the material interfacial layers during the shock interface interactions. Transition involves unsteady large-scale coherent-structure dynamics resolvable by CGS but not by Reynolds-Averaged Navier-Stokes modeling based on equilibrium turbulence assumptions and single-point-closures. We propose a dynamic blended RANS/LES bridging strategy for applications involving variable-density turbulent mixing applications, and report progress testing its implementation for relevant cases prototyping the shock-driven turbulent mixing applications (Computers and Fluids 2020).