An Attempt to Describe Reynolds Stresses of Turbulent Boundary Layer Subjected to Pressure Gradient

The paper is concerned with the issue of scaling of Reynolds stresses and the phenomenon of the outer peak of velocity fluctuations, which appears in adverse pressure gradient conditions. For this purpose, experimental data from favorable and adverse pressure gradient turbulent boundary layers, for Reynolds number varying from \(Re_{\theta }\approx 2300\div 6200\), have been analyzed. At pressure gradient conditions, the self-similarity cannot be obtained using the scale, which is constant across the boundary layer thickness. In this paper, we also propose a modification of the Alfredsson et al. (Eur J Mech B/Fluids 36, 167–175, 2012, [1]) expression, which is dedicated to ZPG flows. The new formulation, utilizing the shape factor H and pressure gradient parameter \(\varLambda \), allows an extension of the validity of Alfredsson et al. proposal for pressure gradient flows.