Abstract

In this study, we discuss the flow field of the realistic city block model planned according to the concept of the future city, in the case of an actual typhoon and a winter monsoon hit. This study applied BCM-LES technique, which enables large scale simulation with high efficient of parallel computing. The fluctuating inflow of the actual typhoon was created by using the method of adding the turbulent component based on WRF-LES. From the computed results, we confirmed that properties of inflow and the location of high-rise buildings affect the flow field and the pressure distribution of target high-rise building.

Abstract

In this study, we investigated the influence of ground surface boundary conditions of the meteorological model on the accuracy in predicting the mean wind speed and wind speed fluctuation in the urban area. Two types of ground surface boundary conditions (Cases 1 and 2) were created. In Case 1, the roughness length for the urban area was set to 0.5 m uniformly, whereas in Case 2, the spatial distribution of roughness length for the urban area was set based on the urban geometry. We performed the wind flow simulation in the central part of Tokyo during Typhoon Lan (2017) by using WRF-LES with the created ground surface boundary conditions. By setting the roughness length based on the urban geometry, the accuracy in predicting the mean wind speed was improved significantly. However, in both cases, WRF-LES underestimated the turbulence intensity, especially near the ground surface.