Experimental study of granular surface flows via a fast camera: A continuous description

Bonamy, Daniel; Daviaud, François; Laurent, L.

doi:10.1063/1.1459720

Cited by 96 publications

(115 citation statements)

References 25 publications

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“…13). Our model is similar to the experimental one of Bonamy et al [6]: 7200 disks (mean diameter equal to 3 mm) are packed in a drum with a diameter of 450 mm. In addition to a frictional contact law, a normal restitution shock law (coefficient equal to 0.92) is postulated and accentuates the dynamic effects.…”

Section: Rotating Drummentioning

confidence: 55%

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Conjugate gradient type algorithms for frictional multi-contact problems: applications to granular materials

Renouf¹,

Alart²

2005

Computer Methods in Applied Mechanics and Engineering

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International audienceThis paper presents gradient type algorithms to solve frictional multi contact problems written as quasi optimization problems. A single loop scheme formally close to the classical conjugate gradient method is proposed with some adap tations of the iterate corrections and gradient projections. Since the convergence is difficult to prove, various tests in the field of granular media are performed with comparison with the non linear Gauss Seidel scheme

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Section: Rotating Drummentioning

confidence: 55%

“…In a second section different whole processes are considered to take into account the variety of granular problems [6,23,34,35]. In these sections the CPG algorithm is essentially compared with the NLGS method generally associated with the NSCD approach [20,30].…”

Section: Numerical Tests In Granular Mechanicsmentioning

confidence: 99%

Conjugate gradient type algorithms for frictional multi-contact problems: applications to granular materials

Renouf¹,

Alart²

2005

Computer Methods in Applied Mechanics and Engineering

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“…[10,11,13,[28][29][30]. To compare and discuss more in details those velocity profiles, we will first refer to the work carried out by Courrech du Pont et al [14] who have defined three flow regimes for a granular avalanche in a fluid based on the fall under gravity of one grain in fluid: a free fall regime for which there is no fluid influence (i.e.…”

Section: Comparison and Discussion On Velocity Profilesmentioning

confidence: 99%

“…Those predictions are no more valid for surface flows on a granular heap. In this case, several studies in heap and rotating drum configurations have indeed revealed both in free fall regime [13,28,30,32] and inertial limit regime [33] that the steady velocity profiles remain located in the vicinity of the surface and are composed of an upper linear part in the flowing layer followed by a lower exponential tail that vanishes with depth in the granular bulk. A phenomenological model succeeds in accounting for the linear profile [29].…”

Section: Comparison and Discussion On Velocity Profilesmentioning

confidence: 99%

Sensitivity to solid volume fraction of gravitational instability in a granular medium

Bonnet¹,

Richard²,

Philippe³

2010

Granular Matter

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We report experimental results on incipient dynamics of gravitational destabilization in an immersed granular medium. Two protocols have been used to reach instability: a progressive loading and a dam-break situation. The instability triggering, analyzed by high-speed imaging and CIV post-processing, reveals distinct dynamical behaviours depending on the initial packing fraction of the medium. Two destabilisation modes have been observed: a surface avalanche and a deeper phenomenon that we called circular collapse.

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“…Understanding how the flowing part interacts with the static part has motivated many experimental works. Different configurations have been investigated: avalanches propagating on a static layer inclined with respect to the horizontal [1, 2, 3], pile collapsing on an horizontal surface [4,5], flows in rotating drums or on a pile [6,7,8,9,10,11]. However, the dynamics observed in these experiments is complex, since the frontier between flow and no-flow evolves both in space and time.…”

mentioning

confidence: 99%

Initiation of granular surface flows in a narrow channel

Jop¹,

Forterre²,

Pouliquen³

2007

Physics of Fluids

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We experimentally investigate how a long granular pile confined in a narrow channel destabilizes when it is inclined above the angle of repose. A uniform flow then develops, which is localized at the free surface. It first accelerates before reaching a steady uniform regime. During this process, an apparent erosion is observed and the thickness of the flowing layer increases. We precisely study the evolution of the vertical velocity profile in this transient regime. The measurements are compared with the prediction of a visco-plastic model [P. Jop, Y. Forterre and O. Pouliquen, Nature 441, 727 (2006)].A characteristic of dry granular materials is that they can behave like a solid or a liquid. A typical situation is obtained when an avalanche is triggered at the surface of a pile. In this case, grains start to move at the free surface, accelerate and put into motion other grains initially static. Understanding how the flowing part interacts with the static part has motivated many experimental works. Different configurations have been investigated: avalanches propagating on a static layer inclined with respect to the horizontal [1, 2, 3], pile collapsing on an horizontal surface [4,5], flows in rotating drums or on a pile [6,7,8,9,10,11]. However, the dynamics observed in these experiments is complex, since the frontier between flow and no-flow evolves both in space and time. Investigating the erosion process in a uniform avalanche, where the flow/no-flow interface varies only in time, is one of the motivation of this study.From a theoretical point of view, different approaches have been proposed to describe the solid-liquid transition. A whole class of models is based on depth averaged equations and writes the mass and momentum equation for the flowing layer and the static pile [12]. In this framework, an additional closure equation has to be proposed to describe the evolution of the interface [13,14,15]. A second approach considers the granular material like a mixture of a liquid and of a solid phase and writes an empirical equation for the liquid phase fraction [16]. This approach captures some non trivial features of the transition between static and flowing regions [16].Recently, it has been shown that for some configurations with sidewalls, the localization of the granular flows on top of a pile is simply related to the non uniform distribution of stresses. Due to the lateral friction, the ratio between shear stress and normal stress decreases when going deeper in the pile. At a critical depth, it reaches the yield threshold and the material stops. Using a visco-plastic rheological model [17,18], quantitative predictions have been obtained for steady uniform flows. One can then wonder if unsteady avalanches, where erosion is observed, can be captured by the same approach. * Electronic address: pierre.jop@polytech.univ-mrs.frTo study initiation of flow, we design an experimental set-up where a long pile confined in a narrow channel is suddenly destabilized above the angle of repose. This configuration allows...

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Experimental study of granular surface flows via a fast camera: A continuous description

Cited by 96 publications

References 25 publications

Conjugate gradient type algorithms for frictional multi-contact problems: applications to granular materials

Conjugate gradient type algorithms for frictional multi-contact problems: applications to granular materials

Sensitivity to solid volume fraction of gravitational instability in a granular medium

Initiation of granular surface flows in a narrow channel

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