Wake-flat Plate Boundary Layer Interaction at Low Reynolds Number

AbstractThe present numerical study has been conducted to observe the unsteady boundary layer characteristics on a flat plate induced by a von Karman vortex street wake. This flow situation is an idealization of that occurring on turbomachinery blades where unsteady wakes are generated by the preceding row of blades. In this research, the boundary layer is developed under zero pressure gradient while the vortex street is generated by an elliptic cylinder positioned in the free stream. The minor-major axes ratio of the elliptic cylinder is taken as 0.6 with an angle of attack 0°. The investigation covers a Reynolds number range up to 1000 based on the focal distance of the elliptic cylinder and free stream velocity. The time dependent, two dimensional flow is simulated numerically using finite element formulation. The development of the flow field up to certain time period is considered. Instantaneous streamlines of the disturbed flow field, instantaneous velocity field, boundary layer integral parameters, and skin friction on different streamwise locations on the plate are presented for different Reynolds numbers. The wake vortices strongly affect the boundary layer over the flat plate