Experimental investigation of the effects of short roughness strip and wall suction on the anisotropy in a turbulent boundary layer

Hot wire measurements have been made in a turbulent boundary layer subjected to a short roughness strip and concentrated suction. The suction is applied through a porous wall strip for a range of suction rate. The aim of the study is to examine the effects of short roughness strip and suction on the anisotropy of Reynolds stress tensor. The result indicates that the anisotropy of Reynolds stress tensor is increased marginally downstream of the combination of suction and roughness strip. Although, roughness strip control the magnitude of the variations of the effect of suction on the anisotropy of Reynolds stress tensor, they act independently on the mechanism of the wall turbulence of the layer. While suction acts to increase the anisotropy, roughness strip act to reduce the anisotropy.