Experimental study of a separating, reattaching, and redeveloping flow over a smoothly contoured ramp

A turbulent boundary layer that separates, reattaches, and redevelops over a smoothly contoured ramp and a downstream Aat plate has been examined. In order to resolve the flow in the viscous sublayer, a custom-built, two-dimensional LDA with a very high resolution was used. A small separation bubble occurred over the trailing edge of the ramp. The <(v'v')over bar> and <(u'v')over bar> Reynolds stress components increased rapidly in the adverse pressure gradient boundary layer, and developed large outer layer peaks aligned with the inflection point in the mean velocity profile. The high stress levels were nearly unchanged by the reattachment process, decaying only after the mean velocity profile recovered and outer-layer production dropped. A key feature is that the inner layer recovered relatively quickly to a typical turbulent boundary layer in the redeveloping region, while the outer layer recovery was retarded by the large eddies generated in the separation region. (C) 2000 Begell House Inc. Published by Elsevier Science Inc. All rights reserved.