Numerical investigation of transitional flow over a rapidly pitching plate

A computational study of a plate undergoing high amplitude, pitch, hold, and return motions is presented. An implicit large eddy simulation (ILES) technique is employed to capture the laminar-to-turbulent transition process as the plate is pitched to high angles of attack. Simulations are performed for Reynolds numbers between 5000 and 40 000 with motion profiles of varying accelerations and hold times. The solutions show extremely favorable flow field comparisons of span-averaged stream-wise velocity and out-of-plane vorticity with available experimental Particle Image Velocimetry (PIV) measurements. At a given Reynolds number, the span-averaged flow fields and aerodynamic loading show little sensitivity to the acceleration of the plate for the motions examined. The three-dimensional flow field structure reveals a very rapid transition process that occurs almost at the onset of motion for the higher Reynolds number cases. In spite of this, the aerodynamic loads for those cases compare closely with the same motions at lower Reynolds numbers.