Effect of turbulent Mach number on the thermodynamic fluctuations in canonical shock-turbulence interaction

Shock waves can generate high levels of turbulent fluctuations in temperature, pressure and other thermodynamic properties. These have significant role in turbulent mixing, heat transfer and acoustic noise in high-speed flows. The thermodynamic fluctuations generated by canonical shock-turbulence interaction are strong functions of the shock strength and the upstream turbulence intensity. For a fixed shock Mach number, the downstream thermodynamic variances, normalized by the upstream turbulence kinetic energy, are found to increase with the incoming turbulent Mach number (M-t). This is in contrast to the trend observed for Reynolds stresses and the turbulent dissipation rate. We use direct numerical simulations and linear interaction analysis to investigate the effect of M-t on the post-shock thermodynamic field. It is found that the presence of small amount of acoustic and entropy fluctuations in the incoming flow can explain the high intensity of the post shock thermodynamic variances in the high M-t cases. (C) 2019 Elsevier Ltd. All rights reserved.