Host: Japan Association for Wind Engineering
Pages 113-114
Wind flow and dispersion characteristics are sensitively changed by advective effects based on the wind flows above and within the urban canopy layers. For the simulation, we use LES simulation and employ the two pattern of the model such as 0degree case (larger aspect area of upwind side) and 90degree case (smaller aspect area of upwind side). From the 0degree simulation (larger aspect area), we found special distinctive phenomena inside the canopy area such as the large scale span wise flow switching from side to side. Those large scale flow is universally and randomly occurred inside the canopy area. In this study, we focus on the trigger of the those characteristics and structure using some kinds of visualization technic, and we reviled the occurrence of flow direction change. At the same time, we consider the dispersion phenomenon. Basically those dispersion characteristics depends on the switching flow but when the both side of switching flow are impinging from the each side of dispersion source, concentration stagnate inside of the canopy and exhaust from upward. This is the mechanism of the suddenly high concentration at back ward blocks.
