000179661 001__ 179661
000179661 005__ 20181203022806.0
000179661 0247_ $$2doi$$a10.2136/vzj2006.0105
000179661 02470 $$2ISI$$a000252596100004
000179661 037__ $$aARTICLE
000179661 245__ $$aMeasurements and Modeling of variable gravity effects on water distribution and flow in unsaturated porous media
000179661 260__ $$c2007
000179661 269__ $$a2007
000179661 336__ $$aJournal Articles
000179661 520__ $$aLiquid 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.
000179661 6531_ $$aHydraulic Conductivity
000179661 6531_ $$aGrowing Plants
000179661 6531_ $$aMicrogravity
000179661 6531_ $$aFlight
000179661 6531_ $$aSpace
000179661 6531_ $$aWheat
000179661 6531_ $$aSoils
000179661 6531_ $$aTube
000179661 6531_ $$aGas
000179661 700__ $$uUtah State Univ, Dept Plants Soils & Climate, Logan, UT 84322 USA$$aHeinse, Robert
000179661 700__ $$uUtah State Univ, Dept Plants Soils & Climate, Logan, UT 84322 USA$$aJones, Scott B.
000179661 700__ $$uUniv Space Res Assoc, NASA JSC, Houston, TX 77058 USA$$aSteinberg, Susan L.
000179661 700__ $$uUniv Arizona, Dept Soil Water & Environm Sci, Tucson, AZ 85721 USA$$aTuller, Markus
000179661 700__ $$g169273$$aOr, Dani$$0244741
000179661 773__ $$j6$$tVadose Zone Journal$$q713-724
000179661 909C0 $$0252157$$pLASEP$$xU11248
000179661 909CO $$particle$$ooai:infoscience.tind.io:179661
000179661 937__ $$aEPFL-ARTICLE-179661
000179661 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000179661 980__ $$aARTICLE