Application of the CFS PML to the FDTD solution of wave-structure interaction problems

When solving wave-structure interaction problems with the FDTD method, the perfectly matched layer (PML) absorbing boundary condition (ABC) can be set quite close to the structure of interest (J.-P. Berenger, IEEE Trans. Ant. and Propag., vol. 44, no. 1, pp. 110-117, 1996), so that the overall computational domain is widely reduced in comparison with previously used ABCs. Nevertheless, the PML must be some cells in thickness and it typically consumes 20-50% of the overall computational time. It would be desirable if this thickness were reduced. From theoretical investigations (J.-P. Berenger, ibid., vol. 47, no. 10, pp. 258-265, 2002), the complex frequency shifted (CFS) PML (M. Kuzuoglu and R. Mittra, IEEE Micr. and Guid. Wave Lett., vol. 6, no. 12, pp. 447-449, 1996) is a candidate in view of achieving such an objective. This is illustrated in the present paper by means of numerical experiments with three-dimensional structures.