The Velocity Distribution in Turbulent Boundary Layer in Diverging Flow (1st Report)

Abstract

In order to study the effect of the thickness of the layer and the pressure gradient on the velocity distribution curve, the experiments are carried out in the boundary layer along the smooth wall in a diverging channel of rectangular section. In order to make the layer thicker, for example, a corrugated plate is laid on the wall up-stream the measuring wall. These experiments cover a range of Reynolds number Uδ/ν from 2×10⁴∼1·3×10⁵ and a range of thickness of layer δ from 6 mm to 60 mm. The effect of the non-dimensional pressure gradient Γ on the velocity curve appears a little later, but if the pressure gradient dp/dx/ρ/2U²<2m^-1, the shape of the non-dimentional velocity distribution has a single family of curves within the discrepancy not exceeding 2∼3%. When the pressure gradient becomes greater, the velocity curve near the wall varies and cannot be fixed by one form parameter.