Home – Home – Jornals – Thermophysics and Aeromechanics 2002 number 2

Wind tunnel data on a vortex shedding at laminar boundary-layer separation behind a backward-facing step on a flat plate are reported. The periodic vortices induced by controlled flow excitation in the region of reattachment are dealt with. Amplitude and phase characteristics of the velocity oscillations at the vortex-shedding frequency are determined and compared with those of the short-wave convective perturbations growing behind the point of separation. The results support the conclusion inferred earlier from experimental data on natural vortex motion that shedding of the vortices and amplification of the wavy disturbances in the separated shear layer may be essentially different instability phenomena.