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DOI | 10.1002/2016WR019815 |
Time scales of relaxation dynamics during transient conditions in two-phase flow | |
Schlueter, Steffen1,2; Berg, Steffen3; Li, Tianyi1; Vogel, Hans-Jorg2,4; Wildenschild, Dorthe1 | |
2017-06-01 | |
发表期刊 | WATER RESOURCES RESEARCH
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ISSN | 0043-1397 |
EISSN | 1944-7973 |
出版年 | 2017 |
卷号 | 53期号:6 |
文章类型 | Article |
语种 | 英语 |
国家 | USA; Germany; Netherlands |
英文摘要 | The relaxation dynamics toward a hydrostatic equilibrium after a change in phase saturation in porous media is governed by fluid reconfiguration at the pore scale. Little is known whether a hydrostatic equilibrium in which all interfaces come to rest is ever reached and which microscopic processes govern the time scales of relaxation. Here we apply fast synchrotron-based X-ray tomography (X-ray CT) to measure the slow relaxation dynamics of fluid interfaces in a glass bead pack after fast drainage of the sample. The relaxation of interfaces triggers internal redistribution of fluids, reduces the surface energy stored in the fluid interfaces, and relaxes the contact angle toward the equilibrium value while the fluid topology remains unchanged. The equilibration of capillary pressures occurs in two stages: (i) a quick relaxation within seconds in which most of the pressure drop that built up during drainage is dissipated, a process that is to fast to be captured with fast X-ray CT, and (ii) a slow relaxation with characteristic time scales of 1-4 h which manifests itself as a spontaneous imbibition process that is well described by the Washburn equation for capillary rise in porous media. The slow relaxation implies that a hydrostatic equilibrium is hardly ever attained in practice when conducting two-phase experiments in which a flux boundary condition is changed from flow to no-flow. Implications for experiments with pressure boundary conditions are discussed. Plain Language Summary What happens to fluids in a porous medium after pumping is stopped? Fast X-ray tomography shows that even in a sample smaller than a sugar cube fluid interfaces continue to move for hours until an optimal fluid configuration is reached. The pace is limited by slow relaxation of dynamic contact angles. Therefore hydrostatic equilibrium, which is the state at which all fluid interfaces come to rest, is hardly ever attained in practice when conducting two-phase flow experiments where the flow is stopped in much larger soil or rock samples. |
领域 | 资源环境 |
收录类别 | SCI-E |
WOS记录号 | WOS:000405997000012 |
WOS关键词 | X-RAY MICROTOMOGRAPHY ; POROUS-MEDIA ; CAPILLARY-PRESSURE ; CONTACT LINE ; DISPLACEMENT ; SATURATION ; REGIMES ; IMPACT ; MODEL ; RISE |
WOS类目 | Environmental Sciences ; Limnology ; Water Resources |
WOS研究方向 | Environmental Sciences & Ecology ; Marine & Freshwater Biology ; Water Resources |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/21391 |
专题 | 资源环境科学 |
作者单位 | 1.Oregon State Univ, Sch Chem Biol & Environm Engn, Corvallis, OR 97331 USA; 2.UFZ Helmholtz Ctr Environm Res, Dept Soil Phys, Halle, Germany; 3.Shell Global Solut Int BV, Rijswijk, Netherlands; 4.Martin Luther Univ Halle Wittenberg, Inst Agrar & Ernahrungswissensch, Halle, Germany |
推荐引用方式 GB/T 7714 | Schlueter, Steffen,Berg, Steffen,Li, Tianyi,et al. Time scales of relaxation dynamics during transient conditions in two-phase flow[J]. WATER RESOURCES RESEARCH,2017,53(6). |
APA | Schlueter, Steffen,Berg, Steffen,Li, Tianyi,Vogel, Hans-Jorg,&Wildenschild, Dorthe.(2017).Time scales of relaxation dynamics during transient conditions in two-phase flow.WATER RESOURCES RESEARCH,53(6). |
MLA | Schlueter, Steffen,et al."Time scales of relaxation dynamics during transient conditions in two-phase flow".WATER RESOURCES RESEARCH 53.6(2017). |
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