On the performance and applicability of nonlinear two-equation turbulence models for urban air quality modelling

It is well known that the commonly used k-epsilon turbulence models yield i naccurate predictions for complex flow fields. One reason for this inaccura cy is the misrepresentation of Reynolds stress differences. Nonlinear turbu lence models are capable to overcome this weakness while being not consider ably more complex. However no comprehensive studies are known which analyze the performance of nonlinear turbulence models for three-dimensional flows around building-shaped structures. In the present study the predictions of the flow around a surface-mounted cube using three nonlinear two-equation turbulence models are discussed. The results are compared with predictions of the standard k-epsilon turbulence model and wind tunnel measurements. It is shown that the use of nonlinear turbulence models an be beneficial in p redicting wind flows around buildings.