Experiments and simulations of molecular mixing in a reattaching shear layer

Experiments and simulations of a turbulent, compressible, re-attaching shear layer were conducted in order to investigate molecular mixing and validate the computational model. Experiments were conducted in a two-stream blow-down type wind-tunnel, with the top stream having a Mach number of 0.5 and two lower-to-upper stream mass flux ratios: 0.22 and 0.11. The two streams were seeded with hydrogen and fluorine respectively and the heat release from the reaction was used as a tracer of the mixed fluid. Molecular mixing was measured using the ``flip experiment'' technique. The experiments were modeled with a compressible large-eddy simulation (LES) solver using the stretched-vortex subgrid-scale model for momentum and scalar transport. The results from the experiments and simulations will be presented and discussed.