Solution stability of iterative schemes utilizing the FFT
The problem of periodicity assumed by the fast Fourier transform (FFT) when applying spectral/FFT methods is investigated by comparison with a method-of-moments (MOM) formulation. A proposed solution has been implemented. The fictitious copies resulting from the application of the FFT are clearly seen to degrade the solution. The MOM solution does not suffer from this. The method proposed by D. T. Borup and O. P. Gandhi (1987) is clearly shown to rectify the problem. However, there is a computational cost as a result of the numerical integration required for the discrete kernel in the problem investigated.