The proposed research includes high-resolution direct numerical simulations (DNS) to complete a study of the effects of high density-ratios on mixing. The proposed simulations aim to investigate the material mixing of two or more incompressible, miscible fluids with different densities as a consequence of stirring by turbulence created by buoyancy forces.

The mixing of two or more miscible fluids with different densities (or molar masses) is of fundamental interest due to occurrence in atmospheric and oceanic flows, supernova formations, combustion and several engineering applications such as in inertial confinement fusion (ICF) capsules. The data will enable an understanding of the asymmetric behavior of mixing at higher density-ratios. In addition, transport equations for the moments of density gradient will provide unique information about the evolution of the high-order statistics of the scalar field and will allow estimation of the validity of the incompressible assumption in high-density ratio turbulence.

All proposed DNS will be performed with the variable-density version of the petascale CFDNS code developed at Los Alamos National Laboratory. The database not only will be used to study the physics of the large-density ratio flows but also will provide fidelity data for verification/calibration of mix models and non-DNS codes, which is very important for the LANL predictive capability within the stewardship mission.