Influences of mesh size and lightning channel length on lightning electromagnetic field calculation using FDTD algorithm

One of the most important problems of FDTD method used in calculation of lightning electromagnetic effects is that the calculation is very expensive, time consuming, and sometimes even impossible due to the computer limitations. Mesh size and lightning channel length can greatly affect calculation speed in lightning electromagnetic field calculation. In this paper, Influences of different mesh sizes and the lightning channel lengths on the calculation have been discussed. Very strait grid can be used in lightning electromagnetic field calculation without any scatter object; however, too strait grid will cause error when scatter object is taken into consideration. The proposed 7500 m channel length is not necessary for lightning electromagnetic field in the vicinity of the channel. Shorter channel can be used to calculate the nearby lightning electromagnetic fields; closer the area we care about is, shorter the channel is necessary.