Numerical Simulation of Sideflash striking on the side wall of tall buildings

Sideflash is a kind of lightning striking on the side wall of tall buildings. This unexpected thunder stroke often leads to big property losses and endangers lives of people. However, the origin and development mechanism of this lightning stroke are still not clear. To simulate the sideflash, a 3-D numerical model of negative cloud-to-ground lightning is built which is composed of two parts: the thundercloud model and the stepped leader model. The thundercloud model is based on the 3-D dynamics and electrification coupled model. And the stepped leader model is based on the Dielectric Breakdown Model (DBM). The Poisson's Equation solved by the Successive Over-Relaxation method is employed to refresh the spatial electric potential field. Finally, some buildings with different heights are set on the ground. In the numerical simulation, some sideflashes are observed. Based on the comparison experiments, the origin of these phenomena is discussed.