Reynolds-stress budgets in an impinging shock-wave/ boundary-layer interaction

Abstract

Wall-resolved large-eddy simulations of an impinging shock-wave/boundary-layer interaction (SBLI) are performed to investigate the evolution of Reynolds stresses. After an assessment of accuracy by comparison with experimental data, mechanisms in the Reynolds-stress transport equation, including production, diffusion, strain, and dissipation are examined. In the upstream boundary layer, these quantities are validated with high confidence against published results from the literature. Concerning the SBLI region, all Reynolds stresses exhibit significant growth, consistent with the enhancement of turbulence in adverse pressure gradients. Of particular note is the pressure strain term, which plays a key role in energy redistribution from ρu00 u00 to ρv00 v00 and ρw00w00. The pressure diffusion term, commonly assumed to be negligible or combined with turbulent diffusion in Reynolds-stress models, becomes larger than the production and pressure strain terms in the region where the impinging shock crosses the shear layer above the separation bubble. Power spectra of u0 in this region show links to shear layer flapping and Kelvin–Helmholtz-type instability. In the vicinity of the growth in pressure diffusion, turbulent mass flux also exhibits amplification. Critically, in the ρu00 v00 budget, pressure diffusion and turbulent mass flux behavior for y > 10 suggests that there may be a benefit in considering the terms individually in modeling efforts.