Extract

This study investigates ventilation performance in parametric urban scenarios using a large-eddy simulation (LES) model. The LES codes are first validated using computational fluid dynamics (CFD) guidelines for building simulations, and then utilized in the simulations of parametric-designed urban configurations. With various combinations of planning parameters, air flows and pedestrian-level velocity ratios in a total of 48 scenarios are investigated. Major findings and recommendations are: First, ground coverage ratio (λp) is the most important factor for good ventilation. Second, the effects of building height differentials and turbulence levels in street canyons on urban ventilation are connected to urban density. Inhomogeneous building heights generate more turbulence in street canyons and have a negative (positive) effect on velocity ratios of low-density (high-density) parametric urban fabrics. The application of this point is that homogeneous building heights are recommended when low density is present, and inhomogeneous building heights may be better in cases of high density.

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