Eric Istasse

Filtration in artificial porous media and natural sands under microgravity conditions

The goal of the present paper is to investigate experimentally and theoretically the capillary driven filtration in porous media with homogeneous and inhomogeneous porosity and permeability under microgravity conditions. The motivation having determined the choice of the environment was to study nonequilibrium phenomena in two-phase filtration in porous media. 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. Theoretical and experimental results on determination of mixing fluxes in two-phase filtration are discussed.

Counterdiffusion protein crystallisation in microgravity and its observation with PromISS (Protein Microscope for the International Space Station)

The crystallisation by counterdiffusion is a very efficient technique for obtaining high-quality protein crystals. A prerequisite for the use of counterdiffusion techniques is that mass transport must be controlled by diffusion alone. Sedimentation and convection can be avoided by either working in gelled systems, working in systems of small dimensions, or in the absence of gravity. We present the results from experiments performed on the ISS using the Protein Microscope for the International Space Station (PromISS), using digital holography to visualise crystal growth processes. We extensively characterised three model proteins for these experiments (cablys3*lysozyme, triose phosphate isomerase, and parvalbumin) and used these to assess the ISS as an environment for crystallisation by counterdiffusion. The possibility to visualise growth and movement of crystals in different types of experiments (capillary counterdiffusion and batch-type) is important, as movement of crystals is clearly not negligible.

The National - ESA Soyuz missions Andromède, Marco Polo, Odissea, Cervantes, DELTA and Eneide

From the autumn of 2001 till spring of 2005 a series of six flights to the International Space Station, ISS, were conducted using the Russian Soyuz manned launcher. These flights initially known as ‘taxi-missions’, were characterized by the participation and co-funding from both the European Space Agency, ESA, and the five national delegations from France, Italy, Belgium, Spain, and the Netherlands. The national participation was reflected both in the flight of a cosmonaut/astronaut, originating from the country co-sponsoring the flight as well as in the origin of the majority of experiments and other activities carried out during these missions. In these six Soyuz missions: Andromède (October 2001), Marco Polo (April 2002), Odissea (October 2002), Cervantes (October 2003), DELTA (April 2004) and Eneide (April 2005), some more than one hundred experiments were carried out. These experiments covered the areas of basic and applied research and technology in biology, human physiology, fluid and plasma physics, material science and Earth observation. Also a significant number of education activities were part of these missions. This paper gives a complete overview of these missions, of all science, education and related activities performed. The perspectives of these activities in the light of the space exploration programs in the XXI century and some of the uncertainties and paradoxes are discussed.

Viscous fingering in miscible liquids under microgravity conditions

Viscous fingering was observed by injecting colored water into a Hele-Shaw cell preliminarily filled with a glycerin-water solution. We varied the viscosity ratio, the flow rate, the gap width, and the density ratio. The Peclet number was higher than 105. Some of the experiments were performed in microgravity conditions (parabolic flights) in order to eliminate the gravity influence on pattern formation. The video shows peculiarities of fingering in microgravity conditions for a gap width of 1.2 mm. The first sequence of two experiments shows the influence of the viscosity ratio, which was decreased by a factor of 10 from the first to the second experiment. The next sequence shows the influence of the flow velocity, which was decreased by a factor of two between the first and second experiments in this sequence.

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

Abstract 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.