Elastic waves in fluid-saturated granular media depend on the rheology which
includes elements representing the fluid and, if necessary, gas bubbles. We
investigated the effect of different rheological schemes, including and excluding the
bubbles, on the linear Frenkel–Biot waves of P1 type. For the wave with
the bubbles the scheme consists of three segments representing the solid
continuum, fluid continuum, and a bubble surrounded by the fluid. We derived the
Nikolaevskiy-type equations describing the velocity of the solid matrix in the
moving reference system. The equations are linearized to yield the decay rate
as a function of the wave
number
. We compared
the
-dependence
for the cases with and without the bubbles, using typical values
of the input mechanical parameters. For the both cases, the
-curve
lies entirely below zero, which is in line with the notion of the elastic wave being an
essentially passive system. We found that the increase of the radius of the bubbles
leads to faster decay, while the increase in the number of the bubbles leads to slower
decay of the elastic wave.
Keywords
Frenkel–Biot's waves, bubbles, rheology, porous media
Department of Mathematics
Kirkuk University
Kirkuk
Iraqi
Computational Engineering and
Science Research Centre
Faculty of Health, Engineering and Sciences
University of Southern Queensland
Toowoomba, Australia
Computational Engineering and
Science Research Centre, Faculty of Health, Engineering and
Sciences
University of Southern Queensland
Toowoomba
Australia