Patterns and flow in frictional fluid dynamics

Sandnes, Bjørnar; Flekkøy, Eirik Grude; Knudsen, Henning Arendt; Måløy, Knut Jørgen; See, Howard

doi:10.1038/ncomms1289

Cited by 146 publications

(197 citation statements)

References 42 publications

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“…In the recent years, a thorough description of the patterns and hydrodynamic regimes have been reported for systems where gas is injected in a saturated granular medium. For injection at a fixed overpressure and grain compacity in a quasibidimensional (Hele-Shaw) cell, a transition has been reported between the viscous and frictional regimes [39], or between a Saffman-Taylor instability, dense suspension fracturing and fingering in a fixed porous medium [40]. When the compacity is not constrained, and the cell gap varies, more regimes can be found, exhibiting a strong coupling between the fluid and grain flows, as well as an expansion and fluidization of the granular bed [41].…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

Flow and fracture in water-saturated, unconstrained granular beds

et al. 2015

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“…Varas et al conducted experiments of air injection into the saturated porous media in a Hele-Shaw cell [30,31] and in a cylinder box [32]. Eriksen [34]. Rust et al developed a closed-system degassing model using volcanic eruption data [35].…”

Section: Introductionmentioning

confidence: 99%

Bridging aero-fracture evolution with the characteristics of the acoustic emissions in a porous medium

et al. 2015

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The characterization and understanding of rock deformation processes due to fluid flow is a challenging problem with numerous applications. The signature of this problem can be found in Earth Science and Physics, notably with applications in natural hazard understanding, mitigation or forecast (e.g., earthquakes, landslides with hydrological control, volcanic eruptions), or in industrial applications such as hydraulic-fracturing, steam-assisted gravity drainage, CO 2 sequestration operations or soil remediation. Here, we investigate the link between the visual deformation and the mechanical wave signals generated due to fluid injection into porous medium. In a rectangular Hele-Shaw Cell, side air injection causes burst movement and compaction of grains along with channeling (creation of high permeability channels empty of grains). During the initial compaction and emergence of the main channel, the hydraulic fracturing in the medium generates a large non-impulsive low frequency signal in the frequency range 100 Hz-10 kHz. When the channel network is established, the relaxation of the surrounding medium causes impulsive aftershock-like events, with high frequency (above 10 kHz) acoustic emissions, the rate of which follows an Omori Law. These signals and observations are comparable to seismicity induced by fluid injection. Compared to the data obtained during hydraulic fracturing operations, low frequency seismicity with evolving spectral characteristics have also been observed. An Omori-like decay of microearthquake rates is also often observed after injection shut-in, with a similar exponent p ≈ 0.5 as observed here, where the decay rate of aftershock follows a scaling law dN/dt ∝ (t − t 0 ) −p . The physical basis for this modified Omori law is explained by pore pressure diffusion affecting the stress relaxation.

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“…T here has long been substantial interest in the wetting of thin liquid films given the rich diversity of phenomena associated with non-linear spreading dynamics, including self-similar fractal assembly, finger patterning and self-organisation [1][2][3][4][5][6] . In addition to their prevalence in nature, their relevance to micro-and nano-scale processes have led to closer scrutiny of such phenomena in the context of microfluidic research [7][8][9][10] .…”

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confidence: 99%

Unique fingering instabilities and soliton-like wave propagation in thin acoustowetting films

et al. 2012

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Acoustic-fluid interactions not only has had a long history but has recently experienced renewed scrutiny because of their vast potential for microscale fluid and particle manipulation. Here we unravel a fascinating and anomalous ensemble of dynamic 'acoustowetting' phenomena in which a thin film drawn from a sessile drop first spreads in opposition to the acoustic wave propagation direction. The advancing film front then exhibits fingering instabilities akin to classical viscous fingering, but arising through a different and novel mechanism: transverse Fresnel diffraction of the underlying acoustic wave. Peculiar 'solitonlike' wave pulses are observed to grow above these fingers, which, on reaching a critical size, translate away along the wave propagation direction. By elucidating the complex hydrodynamics underpinning the spreading, and associated flow reversal and instability phenomena, we offer insight into the possibility of acoustically controlling fast and uniform film spreading, constituting a flexible and powerful alternative for microfluidic transport.

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Patterns and flow in frictional fluid dynamics

Cited by 146 publications

References 42 publications

Flow and fracture in water-saturated, unconstrained granular beds

Flow and fracture in water-saturated, unconstrained granular beds

Bridging aero-fracture evolution with the characteristics of the acoustic emissions in a porous medium

Unique fingering instabilities and soliton-like wave propagation in thin acoustowetting films

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