The infiltration with atmospheric pressure of Dense Non Aqueous Phase Liquid (DNAPL) in a model of porous medium saturated by another liquid is studied when this DNAPL liquid has a contact angle characterizing wetting liquid. The model of the porous medium considered consists of an assembly of solid particles for various forms. The influence of the shape of the particles is studied. The results found show the retention capacity of such porous media in function of the shape of the solid particles.
Multiphase flows in porous media involving immiscible fluids always interest scientists in terms of applied and fundamental point of view. For example, the transport of immiscible fluid with water known as NAPL (Non Aqueous Phase Liquid) is encountered in geomaterials, processes of remediation of the grounds, biofilters employed in waste water treatment, etc. These flows are complex and often unknown because of the large number of physical parameters involved to describe their properties. At the present time, influence of parameters as density, viscosity or nterfacial tension on the infiltration of NAPL into porous media is much studied by several authors [1-6]. Most of these studies are realized at a macroscopic scale. This macroscopic approach does not make it possible to understand the retention of small drops of DNAPL (Dense Non Aqueous Phase Liquid) in the pores of the medium. However, few studies carried out at the scale of the interstices showed the dispersion of the DNAPL as well in experiments and in numerical simulation [7-9].
In this work, we highlight the influence of a parameter which is poorly studied—geometry of the solid particles of porous media—on the infiltration and the dispersion of a drop of DNAPL. Numerical simulation is carried out for various shapes of the solid particles.
2. Problem Position
The fluids used in this study are water (carrier fluid) and the DNAPL (the drop). The density and the viscosity of water are of 998 kg·m–3 and 1 × 10–3 Pa·s. Those of the DNAPL are respectively equal to 1623 kg·m–3 and 0.89 Pa·s. As an example, Perchlorethylen (PCE) possesses similar properties (INERIS, 2002). A contact angle of 65˚ is imposed in order to consider a wetting DNAPL because most DNAPL’s being in nature are wetting.
Figure 1 presents one of the three structures of porous
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