Unstructured grid simulations of spatially evolving supersonic shear layers

Abstract

This research employed an adaptive unstructured finite element grid with a nonlinear monotonic scheme to undertake high-resolution inviscid eddy simulations of spatially evolving supersonic free shear layers. The objectives were to both improve physical understanding and evaluate the simulation fidelity by direct comparisons with detailed experimental measurements. With a physically consistent perturbation model, the compressibility effects on the nature of the shear layer were investigated by testing three different convective Mach numbers, 0.35, 0.45, and 0.7, nonetheless holding velocity and density ratios fixed. Reduction in eddy coherency as compressibility increased was found to be related to modifications in the merging process (slapping vs rotational merges). Turbulence statistics of velocity and mixture fraction exhibited reductions in the peak values of turbulent intensities of transverse velocity and passive scalar as convective Mach number increases, whereas turbulent intensity of streamwise velocity peak values remain constant.