WIND TUNNEL EXPERIMENT ON BULK SCALAR COEFFICIENT OF URBAN-LIKE ROUGHNESS

The authors investigated bulk scalar coefficient (CE) of the street in the 3-D canopy with various conditions of arrangement, plan area density (λp), frontal area index (λf), and variability of model height in a wind tunnel using salinity method. The results can be summarized as follows. 1) The relationships between CE and lf of both staggered and normal arrayed canopy with uniform height shows different tendency. The CE of 3-D canopy of staggered and normal pattern have similar value under the sparse (λf) and dense conditions, in contrast, CE of staggered canopy is higher than that of normal canopy under the condition of λf = 17.4%. 2) CE of uniform canopy is larger than that of canopy with height variation under the condition of λf < 17.4%. In contrast, CE of uniform canopy is smaller than that of canopy with height variation under the condition of λf = 30.9%. Such a tendency is opposite to the result of drag force coefficient.