建筑物上侧击雷电的三维数值模拟

基于三维近地面闪电先导发展随机模式，通过改变先导初始电位和建筑物几何特性，分析各种情况下的侧击雷电发生概率，探讨侧击雷电产生原因及影响因素。结果发现:建筑物尖端电场畸变值是影响侧击雷电产生的重要参量，当下行先导靠近建筑物且传播位置低于建筑物的高度时，建筑侧面电场畸变值达到触发阈值，侧击雷电易产生；下行先导的初始电位以及建筑物几何特性（高度和宽度）是影响侧击雷电发生概率的重要因素，当下行先导初始电位在-9~-3 MV范围内，侧击雷电发生概率呈先增加后降低的趋势，当初始电位为-4.5 MV时，侧击雷电的发生概率达到峰值；当建筑物高度在50~150 m范围内，侧击雷电发生概率随着高度增加呈先增加后减少的趋势；当建筑物高度为100 m时，侧击雷电发生概率达到峰值；当建筑物宽度在30~70 m范围内，侧击雷电发生概率随建筑物宽度呈递减趋势；当建筑物宽度为30 m时，侧击雷电的发生概率达到峰值。

Three-dimensional Numerical Simulation of Side Flash on Buildings

Lightning is among the top ten kinds of natural disasters. Observations show that the connecting of downward leader and upward leader happen on the corner of tall buildings, a few take place on the side of buildings, but the damage of side flash shouldn''t be ignored. As the side of the lightning protection is relatively weak, the side flash brings huge shock wave and strong electromagnetic radiation, causing great threat to buildings and human securities. Therefore, it is necessary to discuss processes and causes of side flash.On the basis of the existing leader developing random pattern of three-dimensional near-ground lightning, keeping other model settings unchanged, by changing initial potential of downward leader and geometrical property, many model studies on the development of occurrence of side flash are carried out, and statistics of the probability of side flash in various circumstances are performed. Results show that electric field strength of the top corner of the building is an important condition for the occurrence of side flash. When the downward leader is close to the building and below the height of the building, the value of electric field will reach the triggering threshold value, and the side flash is prone to take place. Moreover, initial potential of the downward leader and geometrical properties (height and width) of the building are important factors affecting the probability of side flash occurrence. When initial potential of the downward leader is between -9 MV and -3 MV, the probability of side flash increases at first and then decreases. When the initial potential of downward leader is -4.5 MV, the probability of side flash reaches a maximum. When the height of the building is between 50 m and 150 m, the probability of side flash increases at first and then decreases. When the height of the building is 100 m, the probability of side flash reaches a maximum. When the width of the building is between 30 m and 70 m, the probability of side flash decreases with the increase of the width. When the width of the building is 30 m, the probability of side flash reaches a maximum.These results are beneficial for the three-dimensional simulation of different connecting behavior and modifications of the electric field at the building corner, as well as the research on causes and influencing factors of side flash.