Diffusion in Partially-Saturated Porous Materials.
Diffusion in Partially-Saturated Porous Materials.
(1041 K)
Martys, N. S.
Materials and Structures, Vol. 32, 555-562, October
1999.
Keywords:
diffusion; porous media; computer simulation;
diffusivity; conductivity; lattice Boltzmann; binary
mixtures
Abstract:
The diffusive transport of ions in two classes of porous
media was studied as a function of fluid saturation and
wetting properties. A lattice Boltzmann method was used
to model phase separation of a binary mixture, including
wetting effects, in porous media. Diffusive transport is
then evaluated in each separate phase. It is found that
the degree of saturation of each phase can strongly
affect the transport of ions that are limited to
difising in either the wetting or non-wetting phase. At
high saturations, good agreement is found between our
estimates of diffusivity and that predicted by the
semi-empitical Archie's second law. At lower saturations
it is found that Archie's second law breaks down as
percolation effects become important.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899