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Modeling of two‐phase flow in membranes and porous media in microgravity as applied to plant irrigation in space
Author(s) -
Scovazzo Paul,
Illangasekare Tissa H.,
Hoehn Alex,
Todd Paul
Publication year - 2001
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 - 10.1029/2000wr900311
Subject(s) - porous medium , dimensionless quantity , hydraulic conductivity , mechanics , capillary action , flow (mathematics) , acceleration , porosity , geotechnical engineering , materials science , environmental science , physics , thermodynamics , engineering , soil science , classical mechanics , soil water
In traditional applications in soil physics it is convention to scale porous media properties, such as hydraulic conductivity, soil water diffusivity, and capillary head, with the gravitational acceleration. In addition, the Richards equation for water flux in partially saturated porous media also contains a gravity term. With the plans to develop plant habitats in space, such as in the International Space Station, it becomes necessary to evaluate these properties and this equation under conditions of microgravitational acceleration. This article develops models for microgravity steady state two‐phase flow, as found in irrigation systems, that addresses critical design issues. Conventional dimensionless groups in two‐phase mathematical models are scaled with gravity, which must be assigned a value of zero for microgravity modeling. The use of these conventional solutions in microgravity, therefore, is not possible. This article therefore introduces new dimensionless groups for two‐phase models. The microgravity models introduced here determined that in addition to porous media properties, important design factors for microgravity systems include applied water potential and the ratio of inner to outer radii for cylindrical and spherical porous media systems.