EFFECTS OF UPSTREAM TURBULENCE INTENSITY ON AERODYNAMIC LOADS OF LOW-RISE BUILDINGS IN ATMOSPHERIC BOUNDARY LAYER FLOW USING LARGE EDDY SIMULATION

Based on the existing benchmark for low-rise buildings by TTU (Texas tech university), this study numerically investigates the effects of upstream turbulence intensity on the aerodynamic loadings on a low-rise building in the atmospheric boundary layer flow using Large-eddy simulation (LES). The consistent discretizing random flow generation (CDRFG) method was adopted to reproduce the boundary layer turbulence. The effects of upstream turbulence intensity on the wind effects of the low-rise building were investigated in the context of statistical characteristics of wind pressures and flow visualizations. The results show that the LES results agreed well with the wind tunnel tests and on-site measurements, and the variation of peak pressure coefficients between LES and wind tunnel tests is less than 10%, and the variation of fluctuating pressure coefficients is less than 20%. And the increase of turbulence intensity enhanced the fluctuating aerodynamic loadings and negative peak pressure coefficients and reduced the flow reattachment length, while the mean wind pressure coefficients were trivially affected. The extreme value of the negative peak pressure coefficients is around −5, and with the increase of turbulence intensity, the angle between the vortex central line and the edge of roof is reduced from 14.4° to 8.7°. Moreover, the upstream turbulence intensity has significant effects on the non-Gaussian characteristics of wind pressure on the roofs, especially in the separation region. In terms of flow visualizations, the increase of turbulence intensity would mitigate the flow separation and vortex shedding on the roof, and the vortical structures around the roof became more complex and the quantity of small-scale eddies increased, thereby resulting in an increase of wind pressure fluctuations and a decrease of negative peak pressure coefficients and non-Gaussianity. The outcomes of this study revealed the effects and underlying mechanism of upstream turbulence intensity for the aerodynamic loadings on the low-rise building roof, which would facilitate our understanding for the wind-induced disasters of the low-rise building and provide a useful reference for the wind-resistant design and for aerodynamic performance optimization of the low-rise building.