Granular collapse in a fluid: Different flow regimes for an initially dense-packing

Bougouin, Alexis; Lacaze, Laurent

doi:10.1103/physrevfluids.3.064305

Cited by 57 publications

(88 citation statements)

References 32 publications

(122 reference statements)

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“…T t1 may correspond here to the time for the granular medium to expand prior to collapse, since the granular column is initially densely packed (recall that φ = 0.64). Such an observation has already been reported in the case of a fully immersed granular collapse [24,28,41]. The trigger time T t1 is plotted as a function of the Stokes number St in Fig.…”

Section: A Role Of the Initial Aspect Ratiosupporting

confidence: 75%

“…Other configurations share some similarities with the present liquid-saturated granular column, namely, the slumping of a neutrally buoyant suspension [19][20][21][22][23] and the fully immersed granular collapse [24][25][26][27][28][29][30]. In the first case, the density of the interstitial fluid and that of the grains is similar and hence the granular pressure is canceled.…”

Section: Introductionsupporting

confidence: 52%

“…In this section, we thus focus on the continuousavalanche regime in which capillary effects are negligible (Bo 1 and d > d c ). In this case, beyond the initial aspect ratio a, the Stokes number St and the initial volume fraction φ could also influence the flow dynamics as observed and reported in different studies on immersed granular collapses [24,28]. In particular, in the case of debris flows, Rickenmann [3] reported that the presence of liquid could enhance mobility compared with an equivalent dry situation.…”

Section: Continuous-avalanche Regime: the Capillary-free Regimementioning

confidence: 69%

“…2 : 200]. Note that with the present values of (St, ρ p /ρ f ) the dynamics of the collapse may be in the transition region between the viscous regime and the inertial regime, characterized in fully immersed granular flows [28,31].…”

Section: B Dimensional Analysismentioning

confidence: 79%

“…In this configuration, three granular flow regimes are usually defined, namely, the freefall, inertial, and viscous regimes. These regimes are shown to be controlled by (i) the Stokes number St which prescribes the relative influence of the grain inertia and viscous dissipation of the fluid, and (ii) the grain-fluid density ratio [28,31,32]. Moreover, in the viscous regime, the initial volume fraction φ of the granular column has also been shown to play a significant role on the collapse as opposed to the dry case [24].…”

Section: Introductionmentioning

confidence: 98%

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Collapse of a liquid-saturated granular column on a horizontal plane

2019

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Laboratory experiments on the collapse of a liquid-saturated granular column on a horizontal plane are reported. The trigger and the resulting dynamics of the collapse when occurring, as well as the shape of the final deposit, are characterized and analyzed in light of some dimensionless parameters, namely, the "column" Bond number Bo, the grain diameter to capillary length ratio d/l c , the initial aspect ratio a, the Stokes number St, and the initial volume fraction φ, by varying the properties of the interstitial fluid and of the grains, the geometry, and the compaction of the initial granular column. The main contribution of this study is to: (i) provide a diagram of the different regimes of collapse shown to be mostly controlled by capillary effect, (ii) develop simple criteria that capture the transitions between each regime in terms of critical values of the Bond number and the ratio of the grain diameter to the capillary length, (iii) extend a predictive model of the runout for dry collapses to the more general case of liquid-saturated granular collapses, and (iv) quantify the influence of a, St, and φ on the collapse dynamics and the shape of the final deposit in the capillary-free regime. A perspective description of the role of the interstitial fluid on the spreading of the granular medium, and more particularly of the driving role of the fluid, is discussed and argued on the basis of the present set of experiments.

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Section: A Role Of the Initial Aspect Ratiosupporting

confidence: 75%

Section: Introductionsupporting

confidence: 52%

Section: Continuous-avalanche Regime: the Capillary-free Regimementioning

confidence: 69%

Section: B Dimensional Analysismentioning

confidence: 79%

Section: Introductionmentioning

confidence: 98%

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Collapse of a liquid-saturated granular column on a horizontal plane

2019

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Gravity Currents (Particle Driven Flows)

Lacaze,

Balachandar

2024

CISM International Centre for Mechanical Sciences

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Investigation of particle laden gravity currents using the light attenuation technique

et al. 2023

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An extensional use of the light attenuation technique is described to study the dynamics of particle laden flows. The method is validated against an analytical absorption/scattering model. It is then applied to particle laden gravity currents (PLGCs) and provides access to quantitative measurements of the particle mass fraction field. The influence of particle concentration on the turbulent dynamics of the flow and the front velocity are evaluated and discussed. In all experiments heterogeneities in the particle distribution are measured, with the maximum particle concentration in the PLGC front and intermediate particle concentration at the turbulent interface. The results highlight two regimes. In the dilute case, particles have no measurable impact on the turbulent structures observed in the flow nor on the bulk velocity. Particle sedimentation occurs due to mixing between the carrier and surrounding fluids. In the dense case, turbulent structures strongly weaken and the bulk velocity of the PLGC quantitatively decreases as the effective flow viscosity grows.

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Granular collapse in a fluid: Different flow regimes for an initially dense-packing

Abstract: OATAO is an open access repository that collects the work of some Toulouse researchers and makes it freely available over the web where possible.

Cited by 57 publications

References 32 publications

Collapse of a liquid-saturated granular column on a horizontal plane

Collapse of a liquid-saturated granular column on a horizontal plane

Gravity Currents (Particle Driven Flows)

Investigation of particle laden gravity currents using the light attenuation technique

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