EXPERIMENTAL INVESTIGATION OF A 3-DIMENSIONAL BLUFF-BODY WAKE

The flowfield behind the wavy-cylinder geometry has been examined using flow visualization, total pressure surveys, and two-component laser Doppler anemometry. The topology of the boundary-layer separation line is linked to the subsequent three-dimensional development of the mean and turbulent structures of the wake. The formation of trailing streamwise vortices behind the nodal points of separation results in a locally narrower wake, a more rapid wake velocity recovery, and suppression of the turbulence development within the separated boundary layer. The dynamic behavior of the trailing vortices suggests that vortex pairing is suppressed by the presence of an axial strain field. The Reynold stress field in the immediate wake exhibited large spanwise variations even though the wavy-cylinder geometry did not affect the spanwise spacing of the dominant foci structures on the leeward side of the cylinder or the spanwise spacing of the rib vortices located in the braid region between consecutive von Karman vortices.