Numerical analysis of boundary-layer thickness effects on shock wave/turbulent boundary layer interactions

Shock wave/turbulent boundary layer interactions (SWTBLI) in supersonic regimes are critical to the aerodynamic characteristics of high-speed aircraft. Detailed understanding of the interactions facilitates the development of future supersonic and hypersonic vehicles. Direct numerical simulations (DNS) are performed to solve the compressible Navier-Stokes equations for describing SWTBLI over a 24 compression ramp at a freestream Mach number of 2.9. A sixth-order kinetic energy preserving (KEP) scheme and a fifth-order weighted essentially non-oscillatory (WENO) scheme are used for spatial discretization, while a third-order Runge-Kutta method is used for temporal integration. Fully developed turbulent flows are imposed at the inflow using a recycling-rescaling method with a recycling distance of 10. Here, denotes the 99% boundary-layer thickness at the inflow. Three boundary-layer thicknesses are examined. The 99% boundary-layer thicknesses at the reference station (), normalized by the inflow boundary-layer thickness, are 1.17, 1.50, and 1.70. Taylor microscales, Kolmogorov lengths, and Reynolds numbers are evaluated at this station. Simulation results are validated for mean velocity, density-weighted root-mean-square velocity fluctuations, and two-point correlations. Boundary-layer thickness strongly affects SWTBLI near the compression corner, namely thicker boundary layer extends the separation bubble and shifts the initial interaction upstream. To investigate turbulence amplification mechanisms, the turbulent kinetic energy budget is examined. In cases with a thicker boundary layer, production becomes significant near the compression corner, indicating more pronounced turbulence amplification. These findings elucidate the effect of boundary-layer thickness on compressible flow behavior over compression ramps and provide guidance for the aerodynamic design of supersonic and hypersonic intake systems.