Rapid improvements in computational resources and advances in DNS/LES techniques have led improved flow modeling.  In particular, DNS/LES have been used to investigate complex flow interactions such as those between a shock and a turbulent boundary layer.  These studies with homogeneous and shear turbulence have dealt primarily with a mean one- or two-dimensional incoming flow and have revealed the evolution of the turbulent field under rapid rates of strain.  At the same time, there have been recent developments in using micro vortex generators for passive control of shock/boundary-layer interactions, involving both experiment and computations.  The precise mechanisms as to how they function at high speeds remains the subject of debate.  Studies indicate that micro vortex generators modify the inner structure of the boundary layer to make the layer more resistant to separation, such as when a strong shock impinges on it.  Some investigators suggest that the trailing vortices provide the mixing with the freestream to energize the boundary layer.  However, apparently no experimental or computational results have been obtained to support this suggestion.  A practical advantage of micro vortex generators is their small size which results in less drag than their conventional counterparts. Our research objectives for this project are detailed below:

Understand the performance of micro vortex generators in a rapidly evolving, 3D shock/boundary-layer interaction

Develop high-order LES schemes for three-dimensional, rapidly distorted turbulent flows

Validate LES schemes against mean and unsteady data

Understand the effect of rapid cross-stream accelerations on the flowfield unsteadiness downstream of a three-dimensional shock/boundary layer interaction

Elucidate the mean and unsteady flow physics through time- and frequency-domain analysis

Investigate the interactions between shock-induced pressure gradients, flow unsteadiness and flow separation features

Study the relation between flow unsteadiness, intermittent incoming boundary layer velocity profile fullness, and the existence of incoming boundary-layer streaks