Use of material coordinates in porous media solute and water flow

Material coordinates relating to water flow in saturated swelling systems a nd to solute movement during non-steady water flow in unsaturated porous ma terials often simplify descriptions of these processes. Furthermore, they m ay be formulated similarly and result in similar mathematical forms for the flow equations. The analysis may be extended to solute transport during no n-steady flow of water in a deforming system. These space-like coordinates are simply defined and measured. Their use ensures material balance for all entities of concern and, for some important situations, results in a non-l inear diffusion equation that may be solved for many practically important initial and boundary conditions. (C) 2000 Elsevier Science B.V. All rights reserved.