ON THE CONTINUUM MODELING OF POROUS-MEDIA CONTAINING FLUID - A MOLECULAR VIEWPOINT WITH PARTICULAR ATTENTION TO SCALE

Mass conservation and linear momentum balance relations for a porous b ody and any fluid therein, valid at any given length scale in excess o f nearest-neighbour molecular separations, are established in terms of local weighted averages of molecular quantities. The mass density fie ld for the porous body at a given scale is used to identify its bounda ry at this scale, and a porosity field is defined for any pair of dist inct length scales. Specific care is paid to the interpretation of the stress tenser associated with each of the body and fluid at macroscop ic scales, and of the force per unit volume each exerts on the other. Consequences for the usual microscopic and macroscopic viewpoints are explored.