Abstract:
Some poroelastic sediments have relatively high slow-wave speeds and low shear-wave speeds [N. P. Chotiros, J. Acoust. Soc. Am. 97, 199--214 (1995)]. Wave propagation in these kinds of sediments may be modeled efficiently by neglecting shear waves to obtain the equations of motion of poroacoustic media. With this approach, the number of equations is reduced and numerical implementations may use larger grid spaces. Poroacoustic waves satisfy two coupled equations. Poroelastic waves satisfy three coupled equations for two-dimensional problems (the original formulation involves four equations). The equations of poroacoustics are symbolically identical to the equations of acoustics. The poroacoustic wave equation is a vector generalization of the variable density acoustic wave equation [P. G. Bergmann, J. Acoust. Soc. Am. 17, 329--333 (1946)]. The interface conditions between poroacoustic layers are vector generalizations of the interface conditions between fluid layers. The energy flux integral of poroacoustics is a vector generalization of the energy flux integral of acoustics. The equations of motion are in a form suitable for factoring and solving with parabolic equation techniques. [Work supported by ONR.]