Large-eddy simulation of a Mach 6 cylinder wake

The unsteady wake of a circular cylinder at Mach 6 and Reynolds number 5 x 10⁵ (based on free-stream flow conditions and cylinder diameter) is investigated with large-eddy simulation (LES) of the flow. The high-speed cylinder wake has remarkably distinct appearance and dynamics from its low-speed counterpart. Supersonic flow separation on the aft side is accompanied by separation and reattachment shock waves along with formation of symmetric (top/bottom) shear layers. These shear layers intersect at a downstream location at the centerline. Recent experiments of this flow have revealed coherent flow oscillations in the wake, centered around the region of shear layers intersection, with the Strouhal number exhibiting universal behavior. The present effort aims to understand the mechanism sustaining the unsteadiness through the simulation results. Basic flow features from the simulation are found to be in agreement with experimental observations, and a detailed analysis of the results is presently underway. The complete set of computational results along with a discussion will be presented at the meeting.