Development of a k-ε model for the determination of air exchange rates for street canyons

A two-dimensional renormalized-group (RNG) k-epsilon turbulence model was developed to calculate the air exchange rate (ACH) of idealized street canyons. This model was validated against other modelling (large-eddy simulation, LES, and k-epsilon.) and wind tunnel results. It was demonstrated that the current k-epsilon model was able to capture the complicated flow structures inside street canyons whose outputs agreed reasonably well with other modelling and wind tunnel results available in literature. This k-epsilon. model was then applied to calculate the ACH for street canyons of aspect (building-height-to-street-width) ratios 0.5, 1.0, and 2.0. The values of ACH calculated by the current k-epsilon model compared favourably with those calculated by LES in which their differences were less than 20%. Moreover, there was a remarkable saving in computer resources and computation time by using the current k-epsilon. model. (c) 2005 Elsevier Ltd. All rights reserved.