Quality assurance of the prognostic, microscale wind-field model GRAL 14.8 using wind-tunnel data provided by the German VDI guideline 3783-9

A refined microscale flow field model has been implemented in the Lagrangian Particle Model Graz Lagrangian Model (GRAL) to provide flow fields for its dispersion module. The flow field model is based on the Reynolds-averaged Navier-Stokes equations and uses a standard k-ε turbulence model. Model evaluation is a central point for developers. The Association of German Engineers issued an evaluation guideline in 2005, which was used to test model performance. In this work results are presented for the wind-tunnel experiments described in this guideline. These consist of five cases differing with respect to the size, number, and position of obstacle(s). For these experiments GRAL fulfilled the requirements of the guideline, which are based on so-called hit rates computed for each wind component. Moreover, hit rates obtained with GRAL are comparable with the ones obtained by other commercial CFD-models found in the literature.