On a new nonlinear turbulence model for simulating flows around building-shaped structures

Numerical modelling of turbulence plays a crucial role in providing accurate wind fields, which are necessary to predict transport and dispersion of pollutants in the vicinity of buildings reliably. Although the standard k-epsilon has some well-known deficiencies and more elaborate turbulence models have been developed it is still by far the most widely applied in atmospheric flow and dispersion models. The large CPU time requirement of direct numerical simulation (DNS) and large eddy simulation (LES) still prohibits their application to wind engineering problems of practical interest. Many linear two-equation turbulence models have been proposed in recent years to overcome the deficiencies of the standard k-epsilon turbulence model. However, comparison shows that none achieves much greater accuracy in all regions of typical wind engineering flow fields. In this paper, a new nonlinear turbulence model is proposed which leads to improved results compared to a conventional eddy-viscosity scheme. The flows considered for the validation of the new model range from simple shear and boundary layer flows, to flows around arrays of cubic obstacles. The accuracy of the proposed turbulence model is assessed by comparing the numerical results with wind-tunnel measurements. (C) 2000 Elsevier Science Ltd. All rights reserved.