A Note on a Generalized Eddy-Viscosity Hypothesis

Abstract

The standard eddy-viscosity concept postulates that zero velocity gradient is accompanied by zero shear stress. This is not true for many boundary layer flows: wall jets, asymmetric channel flows, countercurrent flows, for example. The generalized eddy-viscosity hypothesis presented in this paper, relaxes this limitation by recognizing the influence of gradients in the turbulent length scale and the shear. With this new eddy-viscosity concept, implemented into the standard k–ε model, predictions of some boundary layer flows are made. The modelling results agree well with measurements, where predictions with the standard eddy-viscosity concept are known to fail.