Turbulent boundary layer/shock wave interaction in a nozzle using a compressible lattice Boltzmann method

The double distribution function lattice Boltzmann method (DDF-LBM) is explored for its potential use in a single expansion ramp nozzle. The main goal is to evaluate how well DDF-LBM can model shock wave/boundary layer interactions (SWBLI), including shock formation and the size of separation bubbles. The method which is validated in a previous paper by the same authors by examining its potential strengths in well-known benchmark problems such as the shock tube and flow around an airfoil, is combined with Spallart-Almaras turbulent model to simulate shock wave and turbulent boundary layer interactions near a nozzle wall. Achieving accurate results required careful attention to spatial discretization, selecting suitable Courant-Friedrichs-Lewy (CFL) numbers, and tuning parameters. The effectiveness of two discretization schemes—the fifth-order weighted essentially non-oscillatory (WENO) and the third-order weighted non-free-parameter dissipation (WNND)—was assessed for capturing key physical phenomena. The influence of the entrance Mach number was also studied to evaluate the method’s ability to predict major flow variations.