An irregular-grid perfectly matched layer absorbing boundary for seismic wave modeling
地震波数值模拟的非规则网格PML吸收边界

The perfectly matched layer(PML)absorbing boundary condition is incorporated into the acoustic grid method,thus resulting in an irregular-grid PML method.The proposed scheme is developed using the local coordinate system based PML splitting equations and integral approaches of the PML equations under a discretization of triangular grid cells.The irregular-grid PML method allows the artificial boundaries to be constructed with arbitrary geometries only if the interested zones are enclosed.We can take a semi-circle rather than a rectangle as the artificial boundary in simulating the 2-D half-space using the proposed scheme.This results in an over 20% reduction of the nodes in the numerical discretization.By using a smoothed artificial boundary,the irregular-grid PML method can also avoid the special treatments for the corners,which lead to complex computer implementations in the conventional PML method.Owing to that the local geometrical coefficients are computed and stored in a table in advance,no extra computational costs arise when we use the irregular-grid PML method rather than the conventional PML method.The 2-D acoustic cases are considered here.