Deceleration Rate Parameter and Algebraic Prediction of Turbulent Boundary Layer

Abstract

The deceleration rate θ1 /λ, which is defined as the ratio of the momentum thickness to the distance where the free-stream velocity is reduced by 10 percent, is shown as an important and handy parameter to describe the development of turbulent boundary layer in an adverse pressure gradient. Using this parameter a simple calculation procedure of turbulent boundary layer is presented. In order to achieve a large inlet/exit velocity ratio, θ1 /λ =0.02 may be recommended, where the influence of wall friction on the development of momentum loss is very small and the shape factor of boundary layer does not increase rapidly.