A PARABOLIC EQUATION FOR PORE-ELASTIC MEDIA

The parabolic equation (PE) method is extended to handle problems invo lving pore-elastic layers [M. A. Blot, ''Theory of propagation of elas tic waves in a fluid-saturated porous solid,'' J. Acoust. Sec. Am. 28, 168-191 (1956)]. The equations of motion are derived for heterogeneou s pore-elastic media. Interface conditions that are appropriate for th e PE method are derived for coupling to fluid and elastic layers. For the two-dimensional geometry (range and depth) that is representative of many problems in ocean acoustics, the equations of motion reduce to three coupled equations that factor into outgoing and incoming wave e quations (the standard formulation has a redundant equation). The outg oing wave equation is solved with the PE method using rational approxi mations. The pore-elastic PE, which is a generalization of the elastic PE, is an efficient approach for solving range-dependent propagation problems involving an ocean overlying a pore-elastic sediment. The sel f-starter is generalized to handle compressional and shear sources in pore-elastic layers. The coefficients of the pore-elastic wave equatio n are derived from a set of natural parameters. (C) 1995 Acoustical So ciety of America.