This paper presents a study of windbreak sheltering effect on the outdoor open space using Computational Fluid Dynamics (CFD) techniques and the wind tunnel experiments carried out for validating the CFD models. Although the influence of a windbreak on the reduction of wind speed is fairly well known, it is still uncertain how this influence will be affected by the buildings in an urban area where the windbreaks are placed for providing better wind comfort to the people in outdoor open space. The objective of this study was, firstly to seek a suitable numerical model for simulating urban wind environment with windbreak’s existence, and secondly to identify the effectiveness of a windbreak in a built-up area regarding to its physical parameters. The principal results drawn from this study are as follows. (1) The KE-Two-Layer model would be the better turbulence model for simulating a domain with both windbreaks and buildings inside. (2) The SMART discretization scheme would be a good choice for the convection discretization in this kind of simulation. (3) The effect of buildings on the flow regime behind windbreak is significant, due to the presence of the standing vortex in front of the building. (4) The distance between the windbreak and the building is a key factor to the reduction of wind speed, instead of the porosity of the windbreak, if the outdoor space is comparatively small.
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