The present work uses computational fluid dynamics (CFD) to study wind flow around a tall building with one side facing the oncoming flow at different values of Reynolds number based on building length. The method of large eddy simulation LES is used to model turbulence to calculate directly the large-scale vortices (large eddies) by solving the filtered, time-dependent Navier-Stokes equations. The smaller, unresolved scales are modeled using Smagorinsky model. The finite volume method is used to solve the basic equations of mass and momentum conservation in the primitive form on a rectangular Cartesian, non uniform grid of 253x184 nodal points. The results include streamlines pattern, mean velocity, pressure coefficient, and turbulent quantities. The model is verified by comparing the results for unsteady two-dimensional flow around a long square cylinder at upstream turbulence intensity 2% and length-to-width ratio 1.0 with the experimental data of previous works. Acceptable quantitative agreement between present results and experimental results are achieved for pressure coefficient. Three different values of length-to-width ratios are used, namely 1, 2, and 3 at Reynolds number , , and respectively. The results show that the magnitude of negative pressure coefficient within the wake increases with the increase of length-to-width ratio. Different upstream turbulence intensities are used, namely 2%, 6%, 10%, 20%, and 30%. Extreme negative pressure coefficients are shown to increase with the increase of upstream turbulence intensity from 2% to 6%. The pressure distributions show no further effect for the increase of upstream turbulent intensity beyond 6%. |
