Green functions of mass diffusion waves in porous media

A formulism of frequency-domain mass diffusion-waves in porous media is derived by means of Fourier transform. In analogy to conventional thermal-wave fields, internally consistent Green functions in Cartesian coordinates for linear mass diffusion-waves is also presented for infinite, semi-infinite and finite-size domains in three-dimensional spaces. The Green functions are utilized to analyze the response of a particular type of mass diffusion physical system to any arbitrary tracer source distributions. This method allows the introduction of frequency-dependent physically intrinsic properties of porous media. The Green functions presented in this letter may significantly advance understanding in linear mass diffusion-wave physics in porous media, and can be applied to retrieve spatial-temporal diffusive-wave fields from ambient mass fluctuations in geological reservoirs. (letter)