INTERCOMPARISON OF NUMERICAL URBAN DISPERSION MODELS ― PART Ⅱ: STREET CANYON IN HANNOVER, GERMANY

摘要

Microscale computational fluid dynamics (CFD) models developed in different European countries were applied to well defined test cases comprising a variety of 2 and 3 dimensional configurations for which measurements from wind tunnel or field studies were available. This paper presents the results of five CFD codes employing the widely used 'standard k-ε-model' (CHENSI, CHENSI-2, MIMO, MISKAM, TASCflow) for a street canyon in Hannover, Germany (GSttinger Strasse). Firstly the characteristics of the flow field predicted by the different codes are compared with high spatial resolution wind tunnel measurements; secondly the calculated concentration fields are compared with field and wind tunnel data. Both agreements (e.g. for the general flow and concentration fields) and disagreements (e.g. for the level of concentration) are observed in the comparison. The discussion aims at explaining the differences along with giving some suggestions to CFD model users on how to calculate such complex flows, but also to experimentalists on where concentration measurements should be taken in order to be more representative for a whole street and to avoid distinct local effects.