The Crank-Nicolson FDTD Method in Cylindrical Coordinates and Its Application to Underwater UXO Detection and Classification Problems

This paper presents the unconditional Crank -Nicolson finite-difference time-domain (CN-FDTD) scheme method in the cylindrical coordinate for solving underwater electromagnetic induction problems. First, a general CN-FDTD formulation is given, and then numerical results are demonstrated for a loop current source excitation in a conducting multilayer structure. The comparisons between CN-FDTD and traditional FDTD methods are given. The studies demonstrate the accuracy and capability of the proposed algorithm for modeling underwater EMI induction problems in the time domain.