Depinning and creeplike motion of wetting fronts in weakly vibrated granular media

Abstract

We study the effect of weak vibrations on the imbibition of water in granular media. In our experiments, we have observed that as soon as the vibration is applied, an initially pinned wetting front advances in the direction of imbibition. We found that the front motion is governed by the avalanches of localized intermittent advances directed at 45° to the imbibition direction. When the rescaled gravitational acceleration of vertical vibrations is in the range of 0.81≤G≤0.95, we observed an almost steady motion of wetting front with a constant velocity v(cr)(G)∝exp(-1/G) during more than 20 min, whereas at lower accelerations (0.5≤G≤0.8) the front velocity decreases in time as v∝t(-δ). We suggest that the steady motion of an imbibition front in a weakly vibrated granular medium can be treated as a creep motion associated with nonthermal temporal fluctuations of packing density in a weakly vibrated granular medium.

Capillary Rise and Oil Recovery under Primary Bjerknes Force Experienced by Bubbles

“…Imbibition is very important, since it is present in many daily activities, such as a drop of coffee on a napkin, wine filtering, fluid transport in plants, water penetration into concrete [1][2] or enhanced oil recovery [3][4][5], among others. However, an extensive research on imbibition processes is focused on the recovery of crude oil from naturally fractured reservoirs, either spontaneous imbibition [6][7] or forced imbibition [8][9][10][11][12][13][14][15].…”

Fractal imbibition in Koch's curve-like capillar tubes

“…Spontaneous capillary imbibition is a transport phenomenon present in a variety of technological applications such as oil recovery, building materials, soil science, textile and hydrology [1]. Due to this diversity of applications, an infinity of theoretical [2][3][4][5][6] and experimental [7][8][9][10][11][12][13][14] studies have been carried out based on the pioneering works of Lucas [15] and Washburn [16] in order to understand the imbibition mechanism and the related phenomena (for review, see [1,17,18], and references therein).…”

“…It was experimentally demonstrated that the imbibition speed becomes slower than that of Lucas-Washburn Regime (x ∝ √ t) [7][8][9][10][11][12][13][14] as a consequence of the heterogeneity of flow in porous media due to the complex network of randomly distributed pores that connect to each other forming tortuous capillaries through which fluid flows. This tortuous path has a fractal character and the Lucas-Washburn equation is scarce to model imbibition process in permeable materials that possess fractal architecture.…”

Depinning and dynamics of imbibition fronts in paper under increasing ambient humidity

“…An advantage of paper wetting experiments is that the wetting front configurations are easily observable in situ, since the associated time and spatial scales are easily accessible in the laboratory studies. Although extensive experimental and theoretical research has been performed in the past decade to understand the dynamics and pinning of imbibition fronts in porous media [7,[12][13][14][15][16][17][18][19], several aspects of related phenomena remain unknown or poorly understood.…”

“…with the scaling exponent in the range of 0.3 δ < 0.5 (see, for review, Ref. [24]), whereas the global front width increases as W ∝ t α , where α is the global growth exponent [14,19]. As the imbibition front advances, the net loss of water mass per unit time due to evaporation increases, because of an increase in the wetted area.…”