On a numerical study of atmospheric 2D and 3D—flows over a complex topography with forest including pollution dispersion

The paper presents a mathematical and numerical investigation of the atmospheric boundary layer (ABL) flow over a complex terrain. Two mathematical models described in details are based upon: (1) full RANS equations written in the conservative form and (2) modification of the RANS equations by Boussinesq approximation re-casted in the non-conservative form. Both models are formulated for an incompressible flow under the indifferent atmospheric stratification together with a simple algebraic turbulence model and a stationary boundary conditions. A pollution dispersion of passive pollutant has been considered as well. Both models have been applied to a real case atmospheric problem: an investigation of the influence of a forest stand on the flow over a complex topography given by a surface coal field located in the North Bohemia. A non-homogeneous forest stand is simulated by a special model based on a source term added to the momentum equations. A forest free area is supposed to be covered by a low vegetation and its influence is simulated by a surface roughness parameter.