Interface Pinning and the Dynamics of Capillary Rise in Porous Media

Delker, Thomas; Pengra, David B.; Wong, Po‐zen

doi:10.1103/physrevlett.76.2902

Cited by 85 publications

(151 citation statements)

References 14 publications

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“…Avalanches and non-Gaussian intermittent velocity fluctuations [8][9][10][11][12][13][14][15][16][17] can arise from the medium heterogeneous structure, which may involve a very wide range of spatial scales, from nanometer pore size to kilometer field scales. A common theoretical approach to study those flows consists in a volume-averaging or homogenization procedure in order to obtain effective behavior at large scale from the up-scaling of microscopic phenomena [18].…”

Section: Introductionmentioning

confidence: 99%

Experimental study of stable imbibition displacements in a model open fracture. II. Scale-dependent avalanche dynamics

2016

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We report the results of an experimental investigation of the spatiotemporal dynamics of stable imbibition fronts in a disordered medium, in the regime of capillary disorder, for a wide range of experimental conditions. We have used silicone oils of various viscosities μ and nearly identical oil-air surface tension, and forced them to slowly invade a model open fracture at very different flow rates v. In this second part of the study we have carried out a scale-dependent statistical analysis of the front dynamics. We have specifically analyzed the influence of μ and v on the statistical properties of the velocity V , the spatial average of the local front velocities over a window of lateral size . We have varied from the local scale defined by our spatial resolution up to the lateral system size L. Even though the imposed flow rate is constant, the signals V (t) present very strong fluctuations which evolve systematically with the parameters μ, v, and . We have verified that the non-Gaussian fluctuations of the global velocity V (t) are very well described by a generalized Gumbel statistics. The asymmetric shape and the exponential tail of those distributions are controlled by the number of effective degrees of freedom of the imbibition fronts, given by N eff = / c (the ratio of the lateral size of the measuring window to the correlation length c ∼ 1/ √ μv). The large correlated excursions of V (t) correspond to global avalanches, which reflect extra displacements of the imbibition fronts. We show that global avalanches are power-law distributed, both in sizes and durations, with robustly defined exponents-independent of μ, v, and . Nevertheless, the exponential upper cutoffs of the distributions evolve systematically with those parameters. We have found, moreover, that maximum sizes ξ S and maximum durations ξ T of global avalanches are not controlled by the same mechanism. While ξ S are also determined by / c , like the amplitude fluctuations of V (t), ξ T and the temporal correlations of V (t) evolve much more strongly with imposed flow rate v than with fluid viscosity μ.

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Section: Introductionmentioning

confidence: 99%

Experimental study of stable imbibition displacements in a model open fracture. II. Scale-dependent avalanche dynamics

2016

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“…The coupling of large strains (up to 20%) to water transport and localization of viscous dissipation at a bottleneck in the material may account for this discrepancy in the wetting stage; indeed, when a bottleneck of size l b dominates water transport, we expect t $ h a l b /D. As drying and wetting in heterogeneous structures are crucially dependent on the distribution of pore structure and connectivity at long times (Delker et al 1996), the large heterogeneity in the drying response seen in our experiments is probably due in part to the heterogeneities in tissue structure from one species to another, combined with the multiplicity of water transport mechanisms, and currently does not allow us to go easily much beyond a scaling approach.…”

Section: Pine Conesmentioning

confidence: 99%

Hygromorphs: from pine cones to biomimetic bilayers

Reyssat

Mahadevan

2009

J. R. Soc. Interface.

404

360

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We consider natural and artificial hygromorphs, objects that respond to environmental humidity by changing their shape. Using the pine cone as an example that opens when dried and closes when wet, we quantify the geometry, mechanics and dynamics of closure and opening at the cell, tissue and organ levels, building on our prior structural knowledge. A simple scaling theory allows us to quantify the hysteretic dynamics of opening and closing. We also show how simple bilayer hygromorphs of paper and polymer show similar behaviour that can be quantified via a theory which couples fluid transport in a porous medium and evaporative flux to mechanics and geometry. Our work unifies varied observations of natural hygromorphs and suggests interesting biomimetic analogues, which we illustrate using an artificial flower with a controllable blooming and closing response.

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“…The designed drainage level is about 1.5 cm higher than the mesh position inside the sample column. Since water can freely flow in or out of the sample column through the mesh, a horizontal wetting front appear inside the soil packing and moves upward due to capillarity [30]. We keep adding water until it rises to a stable height.…”

Section: B Proceduresmentioning

confidence: 99%

Rain water transport and storage in a model sandy soil with hydrogel particle additives

Wei

Durian

2014

Eur. Phys. J. E

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We study rain water infiltration and drainage in a dry model sandy soil with superabsorbent hydrogel particle additives by measuring the mass of retained water for non-ponding rainfall using a self-built 3D laboratory set-up. In the pure model sandy soil, the retained water curve measurements indicate that instead of a stable horizontal wetting front that grows downward uniformly, a narrow fingered flow forms under the top layer of water-saturated soil. This rain water channelization phenomenon not only further reduces the available rain water in the plant root zone, but also affects the efficiency of soil additives, such as superabsorbent hydrogel particles. Our studies show that the shape of the retained water curve for a soil packing with hydrogel particle additives strongly depends on the location and the concentration of the hydrogel particles in the model sandy soil. By carefully choosing the particle size and distribution methods, we may use the swollen hydrogel particles to modify the soil pore structure, to clog or extend the water channels in sandy soils, or to build water reservoirs in the plant root zone.

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Interface Pinning and the Dynamics of Capillary Rise in Porous Media

Cited by 85 publications

References 14 publications

Experimental study of stable imbibition displacements in a model open fracture. II. Scale-dependent avalanche dynamics

Experimental study of stable imbibition displacements in a model open fracture. II. Scale-dependent avalanche dynamics

Hygromorphs: from pine cones to biomimetic bilayers

Rain water transport and storage in a model sandy soil with hydrogel particle additives

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