Homogenization based two-scale modelling of ionic transport in fluid saturated deformable porous media

Abstract

The paper deals with the homogenization and numerical modelling of deformable porous media saturated by two-component electrolytes. The model relevant to the microscopic scale describes steady states of the medium while reflecting essential physical phenomena, namely electrochemical interactions in a dilute Newtonian solvent under assumptions of a small external electrostatic field and slow flow. The homogenization is applied to a linearized micromodel, whereby the thermodynamic equilibrium represents the reference state. Due to the dimensional analysis, scaling of the viscosity and electric permittivityis introduced, so that the limit model retains the characteristic length associated with the pore size and the electric double layer thickness. The homogenized model consists of two weakly coupled parts: the steady flow of the electrolyte can be described in terms of a global pressure and streaming potentials of the two ions, independently of the solid phase deformations which are computed afterwards for the fluid stress acting on pore walls. The two-scale model has been implemented in the Sfepy finite element software. The numerical results show dependence of the homogenized coefficients on the microstructure porosity. By virtue of the corrector result of the homogenization, microscopic responses in a local representative cell can be reconstructed from the macroscopic solutions.