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Microgravity investigations of capillary-driven imbibition and drainage in inhomogeneous porous media

par Smirnov, NICKOLAY ;Nikitin, V. F.;Legros, Jean Claude ;Istasse, Eric ;Schramm, L.;Wassmuth, F.
Référence Acta astronautica, 54, 1, page (39-52)
Publication Publié, 2003

Article révisé par les pairs

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Résumé :

The main focus of the microgravity engineering sciences is the fundamental results obtained in space experiments, which enable one to solve burning terrestrial problems. The goal of the present paper is to investigate experimentally and theoretically the role of capillary forces in filtration of fluids in porous media with inhomogeneous permeability and to learn how the porosity and permeability non-uniformity affects displacement and entrapment of wetting fluids. Microgravity environment having been chosen for the experimental investigations provides the possibility for upscaling pores, thus revealing the processes taking place at a pore level. The presence of capillary forces is the most important factor allowing water and solutions migration to the upper soil layers, thus delivering life to all the plants on the planet. The obtained knowledge of capillary-driven filtration mechanisms allows one to develop optimal irrigation strategies, which is most important in hot desert regions, and to prevent liquid contaminants migrating to the roots of plants. The paper contains the results illustrating the sensitivity of capillary forces to variations of porous media characteristics. The experimental results obtained for fluid imbibition into unsaturated artificial and natural porous media are compared. The mathematical model for multiphase filtration in porous media under non-equilibrium conditions is being developed along with experimental procedures to determine the influence of capillary forces and mixing fluxes. In contrast to the existing theories, the present model does not rely on relative permeability functions for phases. Experimental and theoretical investigations show that zones of lower permeability could serve as capillary traps for wetting fluids. © 2003 Elsevier Ltd. All rights reserved.