Linear analysis and direct numerical simulation (DNS) are used to study the interaction of a shock wave with a turbulent flow. Effects central to shock wave/boundary layer interaction are identified and explained. The quantitative importance of the turbulence anisotropy and the shock oblique angle is demonstrated. Drop in Reynolds shear stress across a normal shock is shown. The implication for Reynolds stress models is discussed. The role of dilatational turbulent fluctuations on turbulence amplification is studied in detail. An explanation is suggested for lower amplification reported in wind-tunnel studies. Linear analysis & DNS are used to demonstrate the considerable influence of entropic fluctuations on turbulence evolution across a shock. Positive correlation between u' and T ' suppress amplification while negative correlation enhances it. Invalidity of Morkovin's hypothesis is demonstrated. A high order scheme is developed to allow strong shock/turbulence interaction. Results are presented for isotropic turbulence/normal shock interaction. (AN).

As a first step to understand the compressibility effects, interaction of isotropic quasi-incompressible turbulence with a weak shock wave was studied by three-dimensional time-dependent direct numerical simulations. In addition, linear analysis was used to study interaction of isotropic turbulence with shock waves of a wide range of strengths. The effects of the fluctuation Mach number M sub t and the average Mach number M sub 1 superscript u of the upstream turbulence on turbulence statistics were investigated. Both numerical simulations and linear analyses of the interaction show that turbulence is enhanced during the interaction with a shock wave. Turbulent kinetic energy (TKE) and transverse vorticity components are amplified, and turbulent length scales are decreased. The predictions of the linear analyses compare favorably with simulation results for flows with M sub t

A nearly homogeneous nearly isotropic compressible turbulent flow interacting with a normal shock wave has been studied experimentally in a large shock tube facility. Spatial resolution of the order of 8 Kolmogorov viscous length scales was achieved in the measurements of turbulence. A variety of turbulence generating grids provide a wide range of turbulence scales. Integral length scales were found to substantially decrease through the interaction with the shock wave in all investigated cases with flow Mach numbers ranging from 0.3 to 0.7 and shock Mach numbers from 1.2 to 1.6. The outcome of the interaction depends strongly on the state of compressibility of the incoming turbulence. The length scales in the lateral direction are amplified at small Mach numbers and attenuated at large Mach numbers. Even at large Mach numbers amplification of lateral length scales has been observed in the case of fine grids. In addition to the interaction with the shock the present work has documented substantial compressibility effects in the incoming homogeneous and isotropic turbulent flow. The decay of Mach number fluctuations was found to follow a power law similar to that describing the decay of incompressible isotropic turbulence. It was found that the decay coefficient and the decay exponent decrease with increasing Mach number while the virtual origin increases with increasing Mach number. A mechanism possibly responsible for these effects appears to be the inherently low growth rate of compressible shear layers emanating from the cylindrical rods of the grid. Briassulis, G. and Agui, J. and Watkins, C. B. and Andreopoulos, Y. Langley Research Center...