Equations of motions for superfluid³He–⁴He solution filled porous media

Abstract

A theory of the propagation of acoustic waves in a porous medium filled with superfluid 3He–4He solution is developed. The elastic coefficients in the system of equations are expressed in terms of physically measurable quantities. The equations obtained describe all volume modes that can propagate in a porous medium saturated with superfluid 3He–4He solution. Finally, derived equations are applied to the most important particular cases when the normal fluid component is locked inside a highly porous medium (aerogel) by viscous forces. The velocities of two longitudinal sound and transverse modes are calculated.