3-D Adaptive Wind Field Simulation Including Eects of Chimney Emissions

Air pollution models usually start from the computation of the velocity eld of the uid. In this paper, we present a model for computing such a eld based on the contribution of the observed wind o w and the vertical buoyancy or momentum plume rise dened by a Gaussian plume model. This initial velocity eld is adjusted to verify incompressibility and impermeabil- ity conditions by using a mass consistent model. In this environmental modelling that occur in a three-dimensional domain dened over complex terrain, a mesh generator capable of adapting itself to the topographical data and to the numerical solution is essential. Here, the unstructured tetrahedral meshes are generated by combining the use of a renemen t/derenemen t algorithm for two-dimensional domains and a tetrahedral mesh generator based on Delaunay triangulation. Occa- sionally in this process, low quality or even inverted elements may appear. For this reason, we have developed a simultaneous untangling and smoothing procedure to optimise the resulting meshes. Once we have constructed the adapted mesh in accordance with the geometrical characteristics of our domain, we use an adaptive local renemen t in the plume trajectory and also for improving the numerical solution. Finally, this model is applied in a test problem.