建筑物高度对上行闪电触发以及传播影响的数值模拟

A numerical simulation of the effects of building height on single upward lightning trigger and propagation

中文关键词:  建筑物高度  上行闪电  触发条件  传播特征  数值模拟

英文关键词:Building height  Upward lightning  Trigger condition  Propagation characteristics  Numerical simulation

中文摘要:

      为了探讨建筑物高度对单个上行闪电触发以及传播的影响,设定了一个固定的背景电场,并结合自行触发的上行闪电随机放电参数化方案,进行了二维高分辨率上行闪电放电的模拟试验。结果表明:(1)上行闪电在初始阶段分支比较少;发展到离地面2 km左右后,闪电开始出现大量的分支,闪电通道开始出现明显的分叉:一部分通道继续向高电荷密度中心垂直传播,另一部分通道绕过高电荷密度中心,向外水平传播;模拟的上行闪电只能垂直传播到4 km处的负电荷中心,不能穿过0电势线向上方的正电荷区传播。(2)建筑物高度对上行闪电的触发起了关键作用,建筑物越高,越容易触发上行闪电。(3)建筑物高度对上行闪电传播具有一定的反作用,随着建筑物高度增高,模拟出的上行闪电的水平和垂直传播距离都有所减小,通道的分形维数变小,通道传播的总长度也逐渐减小。

英文摘要:

      Combined with the stochastic lightning parameterization scheme of self-initiated upward lightning, a fixed background electric field is set, and then 2-dimensional fine-resolution lightning discharge simulations are performed to investigate the effect of building height on single upward lightning trigger and propagation. The results show: (1) The upward lightning branch is less in the initial stage; to about 2 km away from the ground, the upward lightning begins to appear a lot of branch, the lightning channel begins to appear obvious bifurcation: some part of the path transmits to the high charge density centre vertically, and another part of the channel bypasses the high charge density with outward horizontal transmission; the upward lightning vertical transmission reaches only to 4 km, where is the negative charge center located, and it is unable to reach, through the zero potential line, to the positive charge area above. (2) Building height plays a key role in upward lightning trigger, and it is more likely to trigger the upward lightning with the increasing height. And (3) building height has certain adverse effect on upward lightning spread, and with the increase of building height, the horizontal and vertical propagation distance of upward lightning, the fractal dimension and the total propagation length of the lightning channel are all decreased gradually.