LES of the flow and building wall pressures in the center of Tokyo

For strong wind problems in the city, we have to consider the effect of turbulence characteristics for the flow field and wind pressure on a building surface. Consequently, we use large eddy simulation (LES) rather than Reynolds averaged Navier–Stokes (RANS) in order to reproduce non-isotropy and non-stationarity of the actual wind flow field. LES can reproduce these characteristics, but in contrast, it is difficult to manage complicated boundary conditions of building surfaces in an urban area. Therefore, we use geographic information system (GIS) data and nested grid technique of several levels to reproduce building shapes in detail. With these techniques, we can use a fine calculation grid for a target area and carry out LES for the strong wind field in the center of metropolitan Tokyo. Finally, we try to estimate the accuracy of LES by comparing local flow field and the local pressure distribution of LES results with those of field measurement data.