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  4. Measurements and Modeling of variable gravity effects on water distribution and flow in unsaturated porous media
 
research article

Measurements and Modeling of variable gravity effects on water distribution and flow in unsaturated porous media

Heinse, Robert
•
Jones, Scott B.
•
Steinberg, Susan L.
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2007
Vadose Zone Journal

Liquid behavior under reduced gravity conditions is of considerable interest for various components of life-support systems required for manned space missions. High costs and limited opportunities for spaceflight experiments hinder advances in reliable design and operation of elements involving fluids in unsaturated porous media such as plant growth facilities. We used parabolic flight experiments to characterize hydraulic properties under variable gravity conditions deduced from variations in matric potential over a range of water contents. We designed and tested novel measurement cells that allowed dynamic control of water content. Embedded time domain reflectometry probes and fast-responding tensiometers measured changes in water content and matric potential. For near-saturated conditions, we observed rapid establishment of equilibrium matric potentials during the recurring 20-s periods of microgravity. As media water content decreased, the concurrent decrease in hydraulic diffusivity resulted in limited attainment of equilibrium distributions of water content and matric potential in microgravity, and water content heterogeneity within the sample was influenced by the preceding hypergravity phase. For steady fluxes through saturated columns, we observed linear and constant hydraulic gradients during variable gravity, yielding saturated hydraulic conductivities similar to values measured under terrestrial gravity. Our results suggest that water distribution and retention behavior are sensitive to varied gravitational forces, whereas saturated hydraulic conductivity appears to be unaffected. Comparisons between measurements and simulations based on the Richards equation were in reasonable agreement, suggesting that fundamental laws of fluid flow and distribution for macroscopic transport derived on Earth are also applicable in microgravity.

  • Details
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Type
research article
DOI
10.2136/vzj2006.0105
Web of Science ID

WOS:000252596100004

Author(s)
Heinse, Robert
•
Jones, Scott B.
•
Steinberg, Susan L.
•
Tuller, Markus
•
Or, Dani  
Date Issued

2007

Published in
Vadose Zone Journal
Volume

6

Start page

713

End page

724

Subjects

Hydraulic Conductivity

•

Growing Plants

•

Microgravity

•

Flight

•

Space

•

Wheat

•

Soils

•

Tube

•

Gas

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LASEP  
Available on Infoscience
July 4, 2012
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/83426
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