A Sublayer Theory for Fluid Injection Into the Incompressible Turbulent Boundary Layer

Summary A sublayer region is introduced in which the intensity of turbu­ lence grows at a prescribed rate. The decrease in wall shear stress due to fluid injection into the boundary la}^er is found under the hypothesis that the effect of injection is restricted to the sublayer region. Experimental measurements of the velocity profiles with fluid injection substantiate this hypothesis. The theoretical decrease in wall shear stress is in good agreement with experiment; the solution is particularly simple and for small values of the injection parameter it contains no arbitrary param­ eters. The theory provides a similarity parameter which differs from the one in general use.