Flow profile of granular avalanches with imposed vertical vibration

Swisher, Nora; Utter, Brian

doi:10.1007/s10035-014-0488-2

Cited by 12 publications

(10 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the walls are rough, high frequency vibration may reduce the effective friction between con-tacts, while larger displacements are needed to relieve the geometrical frustration of interlocking grains. These observations are consistent with prior measurements of avalanching in a rotating drum which show that amplitude rather than frequency is the relevant control parameter [29] and that small vibrations lead to compaction and strengthening compared to the non-vibrated case [27].…”

Section: A Flow Profilesupporting

confidence: 91%

Planar granular shear flow under external vibration

Hoppmann

Utter

2017

Phys. Rev. E

Self Cite

View full text Add to dashboard Cite

We present results from a planar shear experiment in which a two-dimensional horizontal granular assembly of pentagonal particles sheared between two parallel walls is subjected to external vibration. Particle tracking and photoelastic measurements are used to quantify both grain scale motion and interparticle stresses with and without imposed vibrations. We characterize the particle motion in planar shear and find that flow of these strongly interlocking particles consists of transient vortex motion with a mean flow given by the sum of exponential profiles imposed by the shearing walls. Vibration is applied either through the shearing surface or as bulk vertical vibration of the entire shearing region with dimensionless accelerations Γ=A(2πf)^{2}/g≈0-2. In both cases, increasing amplitude of vibration A at fixed frequency f leads to failure of the force network, reduction in mean stress, and a corresponding reduction in imposed strain. Vibration of the shearing surface is shown to induce the preferential slipping of large-angle force chains. These effects are insensitive to changes in frequency in the range studied (f=30-120 Hz), as sufficiently large displacements are required to relieve the geometrical frustration of the jammed states.

show abstract

Section: A Flow Profilesupporting

confidence: 91%

Planar granular shear flow under external vibration

Hoppmann

Utter

2017

Phys. Rev. E

Self Cite

View full text Add to dashboard Cite

show abstract

“…Of course, heap flows are also induced by vibration. It is a well known fact that granular heap structure shows relaxation to a horizontally-flat surface when subjected to strong vibration, even if the slope is clearly less than θ c [13,[18][19][20][21]. This type of relaxation is ubiquitous in many natural phenomena.…”

Section: Introductionmentioning

confidence: 99%

Laboratory experiment and discrete-element-method simulation of granular-heap flows under vertical vibration

2019

View full text Add to dashboard Cite

Granular flow dynamics on a vertically vibrated pile is studied by means of both laboratory experiments and numerical simulations. As already revealed, the depth-averaged velocity of a fullyfluidized granular pile under strong vibration, which is measured by a high-speed laser profiler in the experiment, can be explained by the nonlinear diffusion transport model proposed by our previous paper (Tsuji et al ., Phys. Rev . Lett. 120, 128001 (2018)). In this paper, we report that a similar transport model can be applied to the relation between the surface velocity and slope in the experiment. These facts are also reproduced by particle-scale numerical simulations based on the discrete element method. In addition, using these numerical results, the velocity profile inside the fluidized pile is measured. As a result, we show that the flow velocity decreases exponentially with depth from the surface of the pile, which means that a clearly fluidized region, also known as shear band structure, is localized around the surface. However, its thickness grows proportionally with the local height of the pile, i.e., the shear band does not consist of a fluidized layer with a constant thickness. From these features, we finally demonstrate that the integration of this exponentiallydecreasing velocity profile is consistent with the depth-averaged velocity predicted by the nonlinear diffusion transport model.

show abstract

“…They conclude that a higher frequency or amplitude decrease the viscosity of granular material, with the vibrational energy, Γ, being the only controlling parameter. Swisher and Utter (), however, observed that high frequencies had a stabilizing effect, allowing the grains to settle into more stable configurations, whereas a higher amplitude destabilized the material, although they note that this effect might be enhanced by the irregular shaped grains they used.…”

Section: Introductionmentioning

confidence: 98%

Central uplift collapse in acoustically fluidized granular targets: Insights from analog modeling

Dörfler

Kenkmann

2020

Meteorit & Planetary Scien

View full text Add to dashboard Cite

Depending on their sizes, impact craters have either simple or complex geometries. Peak‐ring craters such as the Chicxulub impact structure possess a single interior ring of peaks and hills and a flat interior floor. The exact mechanisms leading to the formation of a morphological peak‐ring are still a matter of debate. In this study, analog modeling was used to study the flow field of a collapsing central uplift. A 3‐D‐printed cast was used to bring the analog material in the shape of an overheightened central uplift that was based on numerical modeling. The cast was then quickly removed and the central peak collapsed, forming a flattened broad mound that spread out onto the annular moat of the crater cavity. A subwoofer was used to fluidize the granular target material. The kinematics of the collapse were analyzed with the aid of particle image velocimetry, revealing a downward and outward collapse of the central uplift. This mode of collapse is partly in agreement with numerical models, in particular for the initial and middle phases. The overthrusting of the collapsing central peak onto the inward moving crater floor predicted by numerical modeling was observed, though to a lesser degree. A peak‐ring, however, could not be reproduced since the collapse came to a halt before the central peak was completely leveled. Nevertheless, the method provides qualitative insights into the kinematics of collapse phenomena. This experimental study provides independent support of the theory of acoustic fluidization, in addition to numerical simulations.

show abstract

Flow profile of granular avalanches with imposed vertical vibration

Cited by 12 publications

References 50 publications

Planar granular shear flow under external vibration

Planar granular shear flow under external vibration

Laboratory experiment and discrete-element-method simulation of granular-heap flows under vertical vibration

Central uplift collapse in acoustically fluidized granular targets: Insights from analog modeling

Contact Info

Product

Resources

About