Prediction of turbulent transitional phenomena with a nonlinear eddy-viscosity model

This paper describes a new nonlinear eddy-viscosity model of turbulence designed with a view to predicting flow far from equilibrium, including transition. The scheme follows earlier UMIST practice in adopting a cubic relation between the stress and the strain/ vorticity tensors but broadens the range of flows to which the model applies by including a third transport equation for an anisotropy parameter of the stress field. Applications are shown for transition on a flat plate at different levels of free-stream turbulence, for the normal impingement of a turbulent jet on a flat plate, and for the flow around a turbine blade. The model is shown to generate much more realistic predictions than what is said to be the best of the linear eddy-viscosity schemes.