Effective Modeling for Coarse Grained Simulations of Shock Driven Turbulent 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 ICF capsule implosions. In the coarse grained simulation (CGS) paradigm small scales are presumed enslaved to the dynamics of the largest, or put in other words, the spectral cascade rate of energy (the rate limiting step) is determined by the initial and boundary condition constrained large-scale dynamics. CGS includes classical large-eddy simulation (LES) using explicit subgrid scale (SGS) models, and implicit LES (ILES) relying on SGS modeling implicitly provided by physics capturing numerics. By combining shock and turbulence emulation capabilities based on a single (physics capturing) numerics, ILES provides an effective simulation framework for shock driven turbulent mixing. Beyond the complex multiscale resolution issues of shocks and variable density turbulence, we must address the difficult problem of predicting flow transition promoted by energy deposited at the material interfacial layer during the shock interface interactions. Transition involves unsteady large-scale coherentstructure dynamics capturable by CGS but not by an unsteady Reynolds-Averaged Navier-Stokes (RANS) approach based on single-point-closure modeling. We discuss a dynamic blended hybrid RANS/ILES strategy for applications involving variable-density turbulent mixing applications, and report progress testing their preliminary implementation for relevant canonical problems.