Innovative absorbing-boundary conditions for the efficient FDTDanalysis of lightning-interaction problems

Absorbing boundary conditions are developed for the efficient truncation of three-dimensional finite-difference time-domain (3-D FDTD) meshes, used for the analysis of low-frequency transient problems, such as the lightning interaction with an aircraft. The proposed boundary conditions are combined with an innovative time-marching scheme in order to assure numerical stability of the FDTD procedure for millions of time-iterations. The main advantage of the developed approach consists in the great computer saving allowed in the analysis of FDTD problems in which the space discretization step is several thousands of times smaller than the minimum wavelength excited by the transient source. Numerical applications are included in order to demonstrate the accuracy and efficiency of the proposed method