COMPUTER SIMULATION OF WIND FLOW AROUND A BUILDING

Abstract

With the advancements in computer technology, numerical methods have emerged as an alternative tool to establish better understanding of the complex flow problems such as wind flow around buildings [5]. In this thesis, flow over and around a building is simulated using the FEM-based commercial package, ANSYS, which is based on the k-E: turbulence model. The method described here is computational fluid dynamics (CFD) modeling, used initially in a simplified, 2D form to assess the sensitivity of wind pressure to changes in computational domain size, mesh density and boundary conditions (such as, inlet velocity and surface roughness). The results of the sensitivity analyses are compared with the experimental values and resolved the preceding parameters. Having resolved those modeling issues and once it is found out that the software predicts acceptable pressure distributions, extensive analyses of wind flow around a single 3D-building, of different geometries, are carried out to assess the flow dependence on the building geometry. Flow separation on the roof and sides of the building is captured using the fine mesh but not the coarse mesh. The computed flow features over a 2D building gave exaggerated suctions, over the roof and the leeward wall; whereas, the 3D analysis results have almost agreed with the experimental values and turned out "realistic" distributions. Correlation coefficients are proposed so that they can be used to predict the 3D maximum pressure and suction coefficients on the walls and roof of a building from the corresponding 2D simulations. These correlation coefficients are validated by comparing the 2D and 3D simulation results of an arbitrary building; and, it has been achieved almost perfect agreement, with an insignificant error of -1.7%. Therefore, one can make use of the proposed correlation coefficients; consequently, a huge amount of computer memory and analysis time can be saved.