“…A variety of mesh-generated techniques, such as the boundary element method [13], finite element method [14,15], finite volume method [16,17], and finite difference method [18,19], have been proposed to analyze heterogeneous layered porous media. In contrast with conventional mesh-generated techniques, meshfree approaches have attracted much attention in recent years because of their characteristics of simplicity, meshfree, and the capability to deal with engineering problems with complex geometry [20][21][22][23][24][25][26]. Of the wide variety of meshfree approaches, the Trefftz method is one of the widespread boundary-type meshless methods for dealing with steady-state Laplace-type problems, where computed results are approximated as a series of basis functions, completely satisfying the governing Laplace-type equations [27][28][29].…”