FLOW AND DISPERSAL SIMULATIONS OF THE MOCK URBAN SETTING TEST

An improved version of the microscale flow model MISKAM (Eichhorn and Kniffka, 2007) has been used to simulate three-dimensional wind and turbulence fields for the Mock Urban Setting Test (MUST). The model has been evaluated following the procedures defined in the German guideline for obstacle resolving microscale models. In an earlier study in the framework of COST Action 732 (Goricsan et al., 2007) version 5.01 of MISKAM has already been used to compute flow fields for the MUST set-up. Some deviations between computed and observed wind profiles of the vertical velocity component had been found in the wake of the obstacles. The current study addresses the question whether or not recent improvements of the code will also lead to an improved model performance as far as the MUST case is concerned. MISKAM 6 (3 beta version) now uses refined advection schemes for the transport of momentum and turbulence quantities, both formerly solved by a simple upstream scheme. Preceding the discussion of flow simulations for the MUST set-up, a short summary of the evaluation results according to the German guideline will be given. The last part of the study introduces results of dispersal simulations and comparisons to the MUST wind tunnel data sets. The simulations have been carried out either using the upstream algorithm or the MPDATA scheme with up to 2 corrective steps to reduce numerical diffusion.