Crossover from fingering to fracturing in deformable disordered media

Holtzman, Ran; Juanes, Rubén

doi:10.1103/physreve.82.046305

Cited by 87 publications

(119 citation statements)

References 35 publications

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“…Finally, a new regime was reported in the 2D experiment, with a transition between the growth of an air finger and the fracture of the above granular layer at a given height in the cell. Such patterns as fingering and fracturing have been reported in the literature in deformable, saturated porous media, when varying the grain volume fraction [40,55,56]. These patterns, however, were mainly described for horizontal Hele-Shaw cell, in which buoyancy does not govern the system dynamics.…”

Section: Discussionmentioning

confidence: 88%

Flow and fracture in water-saturated, unconstrained granular beds

et al. 2015

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The injection of gas in a liquid-saturated granular bed gives rise to a wide variety of invasion patterns. Many studies have focused on constrained porous media, in which the grains are fixed in the bed and only the interstitial fluid flows when the gas invades the system. With a free upper boundary, however, the grains can be entrained by the ascending gas or fluid motion, and the competition between the upward motion of grains and sedimentation leads to new patterns. We propose a brief review of the experimental investigation of the dynamics of air rising through a water-saturated, unconstrained granular bed, in both two and three dimensions. After describing the invasion pattern at short and long time, a tentative regime-diagram is proposed. We report original results showing a dependence of the fluidized zone shape, at long times, on the injection flow rate and grain size. A method based on image analysis makes it possible to detect not only the fluidized zone profile in the stationary regime, but also to follow the transient dynamics of its formation. Finally, we describe the degassing dynamics inside the fluidized zone, in the stationary regime. Depending on the experimental conditions, regular bubbling, continuous degassing, intermittent regime or even spontaneous flow-to-fracture transition are observed.

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Section: Discussionmentioning

confidence: 88%

Flow and fracture in water-saturated, unconstrained granular beds

et al. 2015

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“…To rationalize the results, we first define an effective capillary number Ca Ã that reflects the balance between viscous and capillary forces at the scale of the entire cell as the ratio between a characteristic capillary pressure difference for invasion along the displacement front, δP c , and the characteristic viscous pressure loss across the cell in the direction perpendicular to the front, δP v [18,27]. From simple arguments using the classical Laplace pressure and Darcy's law, we propose the scaling δP c ∼γ=r min −γ=r max ∼ γ=d, and δP v ∼ ðη liq QRÞ=ðγbd 3 Þ, leading to…”

Section: Resultsmentioning

confidence: 99%

“…Extensions to the Lenormand diagram have addressed the effects of gravity [16], pore-scale disorder [17,18], fluid compressibility [3,19], the crossover between regimes including the existence of a Ca-dependent crossover length scale [17,18,[20][21][22], and frictional forces between grains leading to a whole new set of displacement patterns [3,[23][24][25][26][27]]. Yet, this wealth of observations has been restricted to a drainage process.…”

Section: Introductionmentioning

confidence: 99%

Stabilizing Fluid-Fluid Displacements in Porous Media Through Wettability Alteration

2015

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We study experimentally how wettability impacts fluid-fluid-displacement patterns in granular media. We inject a low-viscosity fluid (air) into a thin bed of glass beads initially saturated with a more-viscous fluid (a water-glycerol mixture). Chemical treatment of glass surfaces allows us to control the wetting properties of the medium and modify the contact angle θ from 5°(drainage) to 120°(imbibition). We demonstrate that wettability exerts a powerful influence on the invasion morphology of unfavorable mobility displacements: increasing θ stabilizes fluid invasion into the granular pack at all capillary numbers. In particular, we report the striking observation of a stable radial displacement at low capillary numbers, whose origin lies on the cooperative nature of fluid invasion at the pore scale.

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“…Previous research shows that at φ ≈ 1, if confining pressures are high, the particle network can lock. Under these conditions, the gas front cannot mobilize the particles, because the mechanical forces that resist particle displacement are stronger than those generated by bubble expansion, and the gas must advance by invading the porespace [15,17,18]. Importantly, the fracture regime was not observed in experiments with in situ bubble generation.…”

Section: The Role Of Particles On Regime Transitionsmentioning

confidence: 97%

“…The transition from fingering to fracturing has been placed at a packing fraction of 0.9 * RCP [10,12]. At RCP, gas migration patterns depend on the confining pressure [15,17,18]. Specifically, low confining stress allows continued fracturing, while increasing the confining stress causes the granular material to become rigid, and forces the gas to invade the pore space in the form of capillary or viscous fingering.…”

Section: Introductionmentioning

confidence: 99%

Gas migration regimes and outgassing in particle-rich suspensions

et al. 2015

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Understanding how gasses escape from particle-rich suspensions has important applications in nature and industry. Motivated by applications such as outgassing of crystal-rich magmas, we map gas migration patterns in experiments where we vary (1) particle fractions and liquid viscosity (10-500 Pa s), (2) container shape (horizontal parallel plates and upright cylinders), and (3) methods of bubble generation (single bubble injections, and multiple bubble generation with chemical reactions). We identify two successive changes in gas migration behavior that are determined by the normalized particle fraction (relative to random close packing), and are insensitive to liquid viscosity, bubble growth rate or container shape within the explored ranges. The first occurs at the random loose packing, when gas bubbles begin to deform; the second occurs near the random close packing, and is characterized by gas migration in a fracture-like manner. We suggest that changes in gas migration behavior are caused by dilation of the granular network, which locally resists bubble growth. The resulting bubble deformation increases the likelihood of bubble coalescence, and promotes the development of permeable pathways at low porosities. This behavior may explain the efficient loss of volatiles from viscous slurries such as crystal-rich magmas.

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Crossover from fingering to fracturing in deformable disordered media

Cited by 87 publications

References 35 publications

Flow and fracture in water-saturated, unconstrained granular beds

Flow and fracture in water-saturated, unconstrained granular beds

Stabilizing Fluid-Fluid Displacements in Porous Media Through Wettability Alteration

Gas migration regimes and outgassing in particle-rich suspensions

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