Numerical simulation of airflow in the vicinity of several rectangular-shaped buildings and airflow and dispersion around an L-shaped building

A three-dimensional numerical code, FEFLO, which is based on finite element techniques with unstructured tetrahedral grids, has been used to simulate the airflow in the vicinity of several rectangular-shaped buildings. A set of experimental data taken at the EPA Meteorological Wind Tunnel was used to evaluate the numerical code for atmospheric urban airflow modeling. The flow obstacles consisted of various rectangular-shaped blocks immersed in a simulated neutral atmospheric boundary layer. The equations solved were the Reynolds-averaged Navier-Stokes equations with the standard k-epsilon model as the turbulence model. The FEFLO-simulated airflow showed good agreement with observed airflow patterns, including sizes of cavity zones in the lee of the buildings and displacement zones in front of the buildings investigated. Furthermore, the airflow and dispersion around a single L-shaped building on flat terrain with neutral stability and a 5 m/s wind speed was carried out. The L-shaped building was at 45 degrees to the incoming wind. An instantaneous release of gas was considered from the courtyard of the L-shaped building. The Reynolds-averaged Navier-Stokes equations with the standard k-epsilon turbulence model were solved. A large eddy simulation based on the Smagorinsky model was also applied for this case. This scenario has been modeled earlier by others using commercially available codes such as STAR-CD. The computation of the near ground-level concentration fields showed good agreement with the predictions of other CFD models used for near-field atmospheric dispersion.