EDDY VISCOSITY TRANSPORT-EQUATIONS AND THEIR RELATION TO THE K-EPSILON MODEL

A formalism will be presented which allows transforming two-equation e ddy viscosity turbulence models into one-equation models. The transfor mation is based on Bradshaw's assumption that the turbulent shear stre ss is proportional to the turbulent kinetic energy. This assumption is supported by experimental evidence for a large number of boundary lay er flows and has led to improved predictions when incorporated into tw o-equation models of turbulence. Based on it, a new one-equation turbu lence model will be derived from the k-epsilon model. The model will b e tested against the one-equation model of Baldwin and Earth, which is also derived from the k-epsilon model (plus additional assumptions) a nd against its parent two-equation model. It will be shown that the as sumptions involved in the derivation of the Baldwin-Barth model cause significant problems at the edge of a turbulent layer.