Properties of Elastic Waves in a non-Newtonian (Maxwell) Fluid-Saturated Porous Medium
The present study investigates novelties brought about into the classic Biot's theory of propagation of elastic waves in a fluid-saturated porous solid by inclusion of non-Newtonian effects that are important, for example, for hydrocarbons. Based on our previous results (Tsiklauri and Beresnev: 2001, Phys. Rev. E, 63, 046304), we have investigated the propagation of rotational and dilatational elastic waves, through calculating their phase velocities and attenuation coefficients as a function of frequency. We found that the replacement of an ordinary Newtonian fluid by a Maxwell fluid in the fluid-saturated porous solid results in: (a) an overall increase of the phase velocities of both the rotational and dilatational waves. With the increase of frequency these quantities tend to a fixed, higher, as compared to the Newtonian limiting case, level which is not changing with the decrease of the Deborah number $α$. (b) the overall decrease of the attenuation coefficients of both the rotational and dilatational waves. With the increase of frequency these quantities tend to a progressively lower, as compared to the Newtonian limiting case, levels as $α$ decreases. (c) Appearance of oscillations in all physical quantities in the deeply non-Newtonian regime.