Entangled Granular Media

Gravish, Nick; Hu, David L.; Goldman, Daniel I.

doi:10.1002/9781119220510.ch17

Cited by 6 publications

(3 citation statements)

References 83 publications

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“…In nature, the worms are often not isolated but occur as biofilms [12]. Hence, they would be well placed, in the event of being overwhelmed by an unexpected wave, to form the entangled ensembles [31] we have observed—so flocs can be the result of collective behaviour, and as such are a fascinating and novel example of safety in numbers.…”

Section: Resultsmentioning

confidence: 99%

Social flocculation in plant–animal worms

2019

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Individual animals can often move more safely or more efficiently as members of a group. This can be as simple as safety in numbers or as sophisticated as aerodynamic or hydrodynamic cooperation. Here, we show that individual plant–animal worms ( Symsagittifera roscoffensis ) can move to safety more quickly through flocculation. Flocs form in response to turbulence that might otherwise carry these beach-dwelling worms out to sea. They allow the worms to descend much more quickly to the safety of the substrate than single worms could swim. Descent speed increases with floc size such that larger flocs can catch up with smaller ones and engulf them to become even larger and faster. To our knowledge, this is the first demonstration of social flocculation in a wild, multicellular organism. It is also remarkable that such effective flocculation occurs where the components are comparatively large multicellular organisms organized as entangled ensembles.

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Section: Resultsmentioning

confidence: 99%

Social flocculation in plant–animal worms

2019

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“…The V ex of cylinders and spherocylinders has been investigated in the past via semi-analytical calculations, 42 mathematical deduction, 43,44 and MC simulations. 42,45 For a straight spherocylinder with a given aspect ratio a and y = 01, V dex can be expressed by eqn (9).…”

Section: Dimensionless Excluded Volumementioning

confidence: 99%

Numerical modeling of the effects of the shape and aspect ratio of 3D curved fiber on the percolation threshold and electrical conductivity of conductive polymer composites

Yuan,

Chen,

Sun

et al. 2024

Soft Matter

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“…In granular materials, the critical volume fraction at which random packings form depends strongly on the symmetries of the constituent particles [16]. Particle anisometry also results in an increased angle of repose [17,18], even exceeding 90 • for particles with extreme aspect ratio [18], indicating a bulk tensile strength that resists extension even though the particles themselves are purely repulsive [19]. This geometric cohesion results from particle entanglement that constrains orientational rearrangements.…”

Section: Introductionmentioning

confidence: 99%

Excluded area of superellipse sector particles

Kornick

Brzinski

2021

Phys. Rev. E

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Superellipse sector particles (SeSPs) are segments of superelliptical curves that form a tunable set of hard-particle shapes for granular and colloidal systems. SeSPs allow for continuous parameterization of corner sharpness, aspect ratio, and particle curvature; rods, circles, rectangles, and staples are examples of shapes SeSPs can model. We measure the excluded area of SeSPs as a function of opening aperture size, beginning with the special case of semi-circular particles and then generalizing to more angular shapes. The excluded area decreases sigmoidally with increasing opening aperture, with sharper SeSP corners resulting in a sharper decrease. Whether two particles can be placed without overlap depends on both the center-of-mass separation and relative orientation. Radial correlation plots of the allowed configurations reveal circular regions centered at each of the particle's two endpoints that indicate configurations of mutually-entangled particle interactions. Simultaneous entanglement with both endpoints is geometrically impossible; the overlap of these two regions therefore represents an excluded area in which no particles can be placed regardless of orientation. The regions' distinct boundaries indicates a translational frustration with implications for the dynamics of particle rearrangements (e.g. under shear). Representing translational and rotational degrees of freedom as a hypervolume, we find a topological change that suggests geometric frustration arises a phase transition in this space. Together, this work offers a path towards a unified theory for particle shape-control of bulk material properties.

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Entangled Granular Media

Cited by 6 publications

References 83 publications

Social flocculation in plant–animal worms

Social flocculation in plant–animal worms

Numerical modeling of the effects of the shape and aspect ratio of 3D curved fiber on the percolation threshold and electrical conductivity of conductive polymer composites

Excluded area of superellipse sector particles

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