LAUSR

A new multipole perfectly matched layer (PML) formulation is presented. Based on the stretched-coordinate approach, the formulation that utilizes a recursive integration concept in its development, introduces a PML stretching function that is created as the sum of any given number of complex-frequency shifted (CFS) constituent poles. Complete formulae for up to a three-pole formulation, to facilitate its implementation in finite-difference time-domain codes, are developed. The performance of this new multipole formulation compares favorably with existing higher order PMLs that instead utilize stretching functions that are developed as the product of elementary CFS constituent poles. It is argued that the optimization of the new multipole PML (MPML) could be more straightforward when compared to that of a higher order PML due to the absence of extra terms generated by the process of multiplication used in the development of the overall PML stretching function in higher order PMLs. The new MPML is found to perform very well when compared to standard CFS-PMLs requiring equivalent computational resources.