A comparative study of turbulence models for junction flow

A junction flow, experimentally studied by numerous authors and enclosed in the ERCOFTAC test case list, is numerically simulated with the RANS approach. Two differential eddy viscosity models, based on local quantities, are considered in the computations: the one-equation Spalart-Allmaras model and the two equation K-epsilon model proposed by Lam and Bremhorst. The numerical results provided by both the models are compared with the experimental measurements of the pressure and velocity field around the junction reported in the ERCOFTAC date base. This comparison show that, both the models are able to predict a fair estimate of the fluid dynamics field around the junction, nevertheless the high level of eddy viscosity introduced by the turbulence models causes a general under-prediction of the horse-shoe vortex dimension. In this framework the Spalart Allmaras model has provided better performance than the Lam-Bremhorst model.