NEW TIME-SCALE BASED KAPPA-EPSILON-MODEL FOR NEAR-WALL TURBULENCE

A k-epsilon model is proposed for wall-bounded turbulent flows. In thi s model, the eddy viscosity is characterized by a turbulent velocity s cale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale, and no singularity exists at the wall. The dam ping function used in the eddy viscosity is chosen to be a function of R(y) = (k1/2y/nu) instead of y+, as in the Lam and Bremhorst model. H ence, the model could be used for flows with separation. The model con stants used are the same as in the high Reynolds number standard k-eps ilon model. Thus, the proposed model will also be suitable for flows f ar from the wall. Turbulent channel flows al different Reynolds number s and turbulent boundary-layer flows with and without pressure gradien t are calculated. Results show that the model predictions are in good agreement with direct numerical simulation and experimental data.