A Multiresolution Time-Domain Method for LEMP Calculation and Comparison With FDTD

A multiresolution time-domain (MRTD) method is proposed for cloud-to-ground lightning electromagnetic pulse (LEMP) calculation. Scaling function of Daubechies wavelet is chosen for fields expansion, and iterative formulas of MRTD method are derivated in 2-D cylindrical coordinates. First, three double-exponential lightning channel-base current with different rise times have been used for evaluating performance of the finite-difference time-domain (FDTD) method. And then, LEMP of different distances of the lightning channel were calculated with the MRTD method. We examined the MRTD method by comparing the results obtained with the FDTD method. Numerical simulation results show that the MRTD method and FDTD method are consistent with each other for first return stroke, even with a larger grid division. However, for subsequent return stroke, oscillations will be observed in the late response of the waveforms calculated by the FDTD method. Comparing with the FDTD method, the MRTD method suffers less oscillations with the same grid division, and can significantly save both computational memory and CPU time with large gird mesh, as well as good numerical dispersion property.