A Turbulence Model for Recirculating Flow

A simple adjustment is proposed that improves the predictions of the standard k-epsilon turbulence model in the presence of two-dimensional recirculating flow. An eddy Reynolds number calculated from velocity, vorticity, and eddy viscosity is introduced as a scaling parameter for reducing the decay term in the governing equation for the turbulence-energy dissipation rate. Using the adjusted k-epsilon model to compute the flow past a backstep channel expansion, the STEMR finite-difference code gives better predictions for streamlines, velocities, and turbulence energies than it does with the standard k-epsilon model. Computed reattachment lengths compare well with experimental data for channel expansion ratios between 1 and 2.