PML Absorbing Boundary

A per­fect­ly matched lay­er (PML) is an ab­sorb­ing lay­er mod­el that — when placed next to an elas­tic bound­ed do­main — ab­sorbs near­ly per­fect­ly all waves trav­el­ing out­ward from the bound­ed do­main, with­out any re­flec­tion from the in­ter­face be­tween the bound­ed do­main and the PML.

The out­go­ing wave is ab­sorbed and at­ten­u­at­ed in the PML. There is some re­flec­tion of the wave from the fixed out­er bound­ary of the PML, but that re­flect­ed wave can be made as small as de­sired. There­fore, an ac­cu­rate mod­el of an un­bound­ed do­main may be ob­tained even if the PML is placed very close to the ex­ci­ta­tion.