Implementation of the renormalization group (RNG) k-ε turbulence model in GOTHIC/6.lb: solution methods and assessment

In GOTHIC, the standard k-ε model is used to model turbulent flow. In an attempt to enhance the turbulence modelling capabilities of the latest 6.1b version of the code for simulation of mixing driven by highly buoyant discharges, we implemented the renormalization group (RNG). This model, which is only implemented in the 'gas' phase, was tested with different simple test-problems and its predictions were compared to the corresponding ones obtained when the standard k-ε model was used. As expected, the RNG model is less dissipative than the standard k-ε model. However, comparison of code predictions with experimental measurements show that the predictions of the RNG model are better only near the source. Finally, we show how in the framework of this latest code version, one can implement higher-order non-linear turbulence models