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

Numerical modelling of turbulence plays a crucial role in providing accurat e wind fields, which are necessary to predict transport and dispersion of p ollutants in the vicinity of buildings reliably. Although the standard k-ep silon has some well-known deficiencies and more elaborate turbulence models have been developed it is still by far the most widely applied in atmosphe ric flow and dispersion models. The large CPU time requirement of direct nu merical simulation (DNS) and large eddy simulation (LES) still prohibits th eir application to wind engineering problems of practical interest. Many li near two-equation turbulence models have been proposed in recent years to o vercome the deficiencies of the standard k-epsilon turbulence model. Howeve r, comparison shows that none achieves much greater accuracy in all regions of typical wind engineering flow fields. In this paper, a new nonlinear tu rbulence model is proposed which leads to improved results compared to a co nventional eddy-viscosity scheme. The flows considered for the validation o f the new model range from simple shear and boundary layer flows, to flows around arrays of cubic obstacles. The accuracy of the proposed turbulence m odel is assessed by comparing the numerical results with wind-tunnel measur ements. (C) 2000 Elsevier Science Ltd. All rights reserved.