横风环境下方形建筑迎风面雨滴收集率特性分析

Previous researches on wind-driven rain on buildings mainly focus on wind-driven rain distribution on the facades under different environmental conditions and building geometries, but few researchers have analyzed the cause of the distribution. Employing the finite panel method, the catch ratio distribution on the windward facade of a cubic building is calculated, and the cause of the distribution is explained by analyzing the envelop regions bounded by the raindrop trajectories. Results indicate that there are two effects exist in the transformation of the envelop regions from the starting plane to the ending plane, which are named the stretching effect and the distortion effect. When the wind direction angle is 0° and the reference wind speed is 10 m/s, the stretching rates along the height direction and the spanwise direction both reduce from the bottom of the building to the top and middle to the sides. While the absolute distortion angles of the boundaries along the spanwise direction drop from the building's corners to the middle, their absolute values along the height direction increase from the building's center to its sides. As the reference wind speed increases, the stretching rates along the height direction alter from positive values to negative values, and the stretching rates along the spanwise direction decrease. In the spanwise direction, the distortion angles of the borders increase near the top and decrease near the bottom of the building, while the distortion angles of the boundaries along the height direction increase near the ground and decrease near the top of the building. When the wind direction angle is 30°, the stretching rates along the height direction increase from the upwind side to the downwind side, as well as the distortion angles of the boundaries along the height and spanwise directions. Moreover, the stretching rates along the spanwise direction increase from the sides to the middle. The results provide theoretical bases for further investigating the influence of building layouts on the catch ratio distribution, and designing the rain shielding structures of buildings.