LES of flows over urban-like roughness blocks

ABSTRACT: In the case of the strong wind problem in the city, we would use LES rather than RANS, in order to reproduce non-isotropy and non-stationary of real wind flow. LES can reproduce these characteristics, but it is difficult to deal with boundary condition on building surface. Therefore, we use nested grids technique of several levels to reproduce the building surface in detail. Using this technique, we can use fine calculation grid and we can put the grid on very near boundary surface. As a result, we can simulate the complex flow in the center of the metropolitan Tokyo with high accuracy. Wind velocity and wind direction were measured at two places in this area, and we estimate the accuracy of this method by comparing the field measurement data with the calculation result. In addition, the wind pressure data on the building surface were measured in the previous study, and we confirm the accuracy for the prediction of the wind pressure by this method.