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Microgravity effects on water flow and distribution in unsaturated porous media: Analyses of flight experiments
Author(s) -
Jones Scott B.,
Or Dani
Publication year - 1999
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/1998wr900091
Subject(s) - hydraulic conductivity , porous medium , capillary action , spacecraft , characterisation of pore space in soil , mechanics , flow (mathematics) , porosity , hysteresis , space shuttle , environmental science , materials science , geotechnical engineering , aerospace engineering , physics , geology , soil science , soil water , composite material , engineering , quantum mechanics
Plants grown in porous media are part of a bioregenerative life support system designed for long‐duration space missions. Reduced gravity conditions of orbiting spacecraft (microgravity) alter several aspects of liquid flow and distribution within partially saturated porous media. The objectives of this study were to evaluate the suitability of conventional capillary flow theory in simulating water distribution in porous media measured in a microgravity environment. Data from experiments aboard the Russian space station Mir and a U.S. space shuttle were simulated by elimination of the gravitational term from the Richards equation. Qualitative comparisons with media hydraulic parameters measured on Earth suggest narrower pore size distributions and inactive or nonparticipating large pores in microgravity. Evidence of accentuated hysteresis, altered soil‐water characteristic, and reduced unsaturated hydraulic conductivity from microgravity simulations may be attributable to a number of proposed secondary mechanisms. These are likely spawned by enhanced and modified paths of interfacial flows and an altered force ratio of capillary to body forces in microgravity.