2D Mixed Hybrid FEM of Lanir Model

Osmoelastic media have large negatively charged groups attached to the solid matrix. Due to the fixed charges, the total ion concentration inside the medium is higher than in the surrounding fluid. This excess of ion particles leads to an osmotic pressure difference, which causes swelling of the medium. Lanir's osmoelastic model assumes that small ions are always in equilibrium with the external salt concentration. This means that ion contribution is neglected and the medium is described by two constituents only: the solid and the fluid. In this paper, we implemented Lanir model using MHFEM (Mixed Hybrid Finite Element Method) for consolidation experiment in both 1D and 2D cases, with result verification with analytical solution in 1D. The constituents are assumed to be incompressible. Infinitesimal deformations are assumed. The material is linear elastic, isothermal, isotropic, homogeneous and fully saturated.