EFFECTS OF WAVES ON THE WAKE OF A SURFACE-PIERCING FLAT-PLATE - EXPERIMENT AND THEORY

Results are presented from a towing-tank experiment conducted in order to document the effects of waves on the wake of a surface-piercing bo dy. A unique, simple model geometry is utilized which makes it possibl e to isolate and identify the most important features of the wave-indu ced effects. Measurements were made for three wave-steepness condition s: zero, medium, and large. The effects of the waves for the latter tw o conditions are shown to be significant. In particular, the variation s of the external-flow pressure gradients cause acceleration and decel eration phases of the streamwise velocity component and alternating di rection of the crossflow, which results in large oscillations of the d isplacement thickness and wake centerplane velocities as compared to t he zero-steepness condition. Remarkably, the wake displays a greater r esponse, that is, a bias with regard to favorable as compared to adver se pressure gradients. The measurements are compared and close agreeme nt is demonstrated with results from Reynolds-averaged Navier-Stokes c alculations. Additional calculations are presented, including laminar- flow results, which aid in explicating the characteristics of the near and intermediate wake, the periodic nature of the far wake, and wave- induced separation. Previously, experimental and computational results were presented for the boundary-layer region.