Turbulent Boundary Layers In Strong Adverse Pressure Gradients

A new analysis of equilibrium boundary layers based on the Schoheld and Perry defect law for flow in moderate to strong adverse pressure gradient is presented. The conditions derived for self-preserving or precise equilibrium boundary layers differ from those given by previous analyses based on the usual velocity defect law. It is shown that nine observed boundary layers on smooth walls conform to these new conditions for equilibrium flow. As the analytical expression for the Schofield and Perry defect law does not vary with pressure gradient an explicit expression for the shear stress profile in any equilibrium layer can be derived. Predicted shear stress profiles show good agreement with experimental data. Limits for the flow parameters within which equilibrium boundary layers can exist are derived and it is shown that observed boundary layers fall within these limits. Results by previous workers are shown to be consistent with these limits.