Laminarization of Turbulent Boundary Layer on Flexible and Rigid Surfaces

An investigation of the control of turbulent boundary-layer e ow over e exible and rigid surfaces downstream of a concave‐convex geometry has been made. The concave ‐convex curvature induces centrifugal forces and a pressure gradient that affect the growth of the turbulent boundary layer. The favorable gradient is not sufe cient to overcome the unfavorable one; thus, the net effect is a destabilization of the e ow into G¨ ortler instabilities. This study shows that control of the turbulent boundary layer and structural loading can be successfully achieved by using localized surface heating because the subsequent cooling and geometrical shaping downstream over a favorable pressure gradient are effective in laminarization of the turbulence. Wires embedded in a thermally insulated substrate provide surface heating. The laminarized velocity proe le lowers the Reynolds number, and it reduces the structure loading. In the laminarization, the turbulent energy is dissipated by the molecular transport due to both viscous and conductivity mechanisms. Laminarization also reduces spanwise vorticity because of the longitudinal temperature gradient of the sublayer proe le. The results demonstrate that the curvature-induced mean pressure gradient enhances the receptivity of the e ow to a localized surface heating, a potentially viable mechanism to laminarize turbulent boundary-layer e ow; thus, the laminarized e ow reduces the response of the e exible structure and the resultant sound radiation.