Development of customized shear layers on smooth and rough surfaces

Shear layers having different structural properties were produced downstream of devices used to artificially thicken turbulent boundary layers. The means used to produce different structural characteristics are described, along with the effects of changes in structure on wall heat transfer. Results from layers developing over smooth and rough surfaces indicate that alterations of artificial thickening device geometry resulted in larger variations in wall heat transfer near smooth surfaces. The most significant of these occured when alterations were made of inner boundary layer regions, where mean velocity shows a logarithmic dependence on distance from the wall. Outer region changes in mean velocity and turbulence profiles resulted in less significant changes in wall heat transfer, particularly in the flows over the rough wall.