Numerical simulation of water drainage in double-porosity soils
Résumé
The paper deals with modelling of unsaturated water flow in soils which are composed of two distinct sub-domains of very different hydraulic properties (double-porosity soils). Flow in such media is often characterized by the local non-equilibrium of the capillary pressure in the two regions, which cannot be described by the local equilibrium model [4]. Recently, a non-equilibrium model based on the homogenization approach has been proposed [5]. In the present paper, the model is applied to simulate gravitational drainage in a particular case of double-porosity medium. The medium consists of highly conductive sand matrix with weakly conductive spherical inclusions arranged in a periodic manner. The numerical simulations have been performed with the DPOR-1D code [11]. Calculation of the effective parameters of the medium is presented as well as the solution of the macroscopic boundary value problem. The behaviour of the double-porosity medium is compared with the behaviour of single-porosity media, i.e. a homogeneous sand and a sand with impermeable inclusions. The results show the importance of the non-equilibrium effects for the flow in double-porosity soils.