Large Eddy Simulation of Turbulent Flows and Pressures on a Cube in an Artificial Wind

摘要

This paper discusses the applicability of LES to turbulent flows and pressures on a cube in natural wind. The turbulent flow around a cube is simulated using LES, and compared with the full-scale measurement data for a 6m cube in the meadow by the group of Silsoe Research Institute. On the basis of the computed flow patterns, the characteristic of pressure on the roof are discussed. The mean velocity profile, turbulent intensity at the cube height and the fluctuation velocity power spectrum agree to the measurement result well at the inflow boundary layer. However, the distribution of computed pressure coefficients become almost flat. On the other hand, the full-scale measurement shows strong negative pressure occurs in the upwind region of the roof. In order to reproduce the characteristic of the pressure distribution on the roof we computed LES with the following modification. 1. Higher resolution for the upwind region of a cube as well as near-cube region. 2. The larger ratio of the boundary layer thickness to cube height. The instantaneous reattachment can be seen and it is expected that separated shear layers were reattached by sufficient time passing.