Atomic scale mixing for inertial confinement fusion associated hydro instabilities

Hydro instabilities have been identified as a potential cause of performance degradation in inertial confinement fusion (ICF) experiments. We study instabilities associated with a single Richtmyer-Meshkov (RM) interface in a circular geometry, idealized from an ICF geometry. In an ICF application, atomic level mix, as an input to nuclear burn, is an important, but difficult to compute, variable. We find numerical convergence for this important quantity, in a purely hydro study, with only a mild dependence on the Reynolds number of the flow, in the high Reynolds number limit We also find that mixing properties show a strong sensitivity to turbulent transport parameters; this sensitivity translates into an algorithmic dependence and a nonuniqueness of solutions for nominally converged solutions. It is thus a complication to any verification and validation program. To resolve the nonuniqueness of the solution, we propose a validation program with an extrapolation component, linking turbulent transport quantities in experimental regimes to mildly perturbed turbulent transport values in ICF Reynolds number regimes. In view of the observed solution nonuniqueness, the validation program and its justification from the results presented here, has a fundamental significance. (c) 2013 Elsevier B.V. All rights reserved.