Influence of turbulence closure on the simulation of flow and dispersion in complex terrain

A dispersion simulation test for the RAMS-MIRS-SPRAY (RMS) modelling system in real complex terrain is presented. As a test case the TRACT campaign was chosen because this data set allows the comparison of both the meteorological variables and the tracer concentrations. Particular attention was focused on testing alternative turbulence closures and assessing their influence on modelling both the meteorology and the dispersion. Firstly, the different turbulence closures introduced in the meteorological model are compared. Secondly, the dispersion simulations are performed using the turbulence provided by the different models. It is demonstrated that using different closure models for turbulence modifies also the mean flow. Concerning the tracer dispersion, the new closures utilising a fully 3D equation for the turbulent kinetic energy seem to give promising results.