Modelling of turbulent energy flux in canonical shock-turbulence interaction

High-speed turbulent flows often encounter high heat loads due to the presence of shock waves. The turbulent energy flux correlation in the mean energy conservation equation is a key unclosed term that determines the heat transfer rate. In this work, we employ existing turbulence models to predict the turbulent energy flux in canonical shock-turbulence interaction. The shortcomings of these models are highlighted, and a new heat-flux limiter model is proposed with the aid of linear theory results. We also write the transport equation for the turbulent energy flux across a shock wave and use it to develop a physics-based model for the same. It is found to predict the peak energy flux at the shock wave and its variation in the acoustic-adjustment region behind the shock. Numerical error incurred while solving the model equations at a shock wave are analyzed and a numerically robust model is obtained by eliminating the nonconservative source terms. The model predictions are compared with available direct numerical simulation data and a good match is obtained for a range of Mach numbers.