Mixed finite element formulation for non-isothermal porous media in dynamics

We present a mixed finite element formulation for the spatial discretization in dynamic analysis of non-isothermal variably saturated porous media using different order of approximating functions for solid displacements and fluid pressures/temperature. It is known in fact that there are limitations on the approximating functions Nu and Np for dis- placements and pressures if the Babuska-Brezzi convergence conditions or their equivalent [1] are to be satisfied. Although this formulation complicates the numerical implementa- tion compared to equal order of interpolation, it provides competitive advantages e.g. in speed of computation, accuracy and convergence