Performance evaluation and absorption enhancement of the Grote-Keller and unsplit PML boundary conditions for the 3-D FDTD method in spherical coordinates

A new absorption performance evaluation of the exact Grote and Keller bound ary conditions versus a recent generalization of the unsplit PML for the FD TD method in spherical coordinates, is thoroughly conducted in this paper. The attenuation capabilities of the latter absorber are further enhanced vi a novel approaches concerning its termination by the Bayliss-Turkel ABC's, in conjunction,vith higher-order finite difference schemes in the layer. Mo reover, an expanded curvilinear mesh algorithm for the interior of the PML is introduced in order to achieve the required reflection with a reduced nu mber of cells. Numerical vector spherical-wave simulations investigate the con vergence properties in respect to grid resolution of both ABC's, the ev olution of various error norms, and their behavior as a function of distanc e from the scatterer, with the 3-D curvilinear FDTD method. Numerical resul ts demonstrate that both conditions are remarkably robust and highly accura te, while the proposed developments provide significant savings in the comp utational cost.