51
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Liu SY, Guillard F, Marks B, Rognon P, Einav I. Experimental study of shear rate dependence in perpetually sheared granular matter. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201714003059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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52
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Stannarius R, Fischer D, Börzsönyi T. Heaping and secondary flows in sheared granular materials. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201714003025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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53
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Berzi D, Thai-Quang N, Guo Y, Curtis J. Stresses and orientational order in shearing flows of granular liquid crystals. Phys Rev E 2016; 93:040901. [PMID: 27176244 DOI: 10.1103/physreve.93.040901] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Indexed: 11/07/2022]
Abstract
We perform discrete element simulations of homogeneous shearing of frictionless cylinders and show that the particles are characterized by orientational order and form a granular liquid crystal. For elongated and flat cylinders, the alignment is in the plane of shearing, while cylinders having an aspect ratio equal to 1 and 0.8 show no orientational order. We show that the particle pressure is insensitive to the cylinder aspect ratio and well predicted by the kinetic theory of granular gases, with a singularity in the radial distribution function at contact different from that for frictionless spheres. The numerical results quantitatively agree with physical experiments on different geometries. The particle shear stress is affected by orientational anisotropy. We postulate that, for frictionless cylinders, the viscosity is roughly due to the motion of the orientationally disordered fraction of the particles, and show that it is proportional, through the order parameter, to the expression of kinetic theory. Finally, we suggest that the orientational order is the result of the competing effects of the shear rate, which induces alignment, and the granular temperature, which ramdomizes.
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Affiliation(s)
- Diego Berzi
- Department of Civil and Environmental Engineering, Politecnico di Milano, 20133 Milano, Italy
| | - Nha Thai-Quang
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Yu Guo
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Jennifer Curtis
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
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54
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Tune DD, Stolz BW, Pfohl M, Flavel BS. Dry shear aligning: a simple and versatile method to smooth and align the surfaces of carbon nanotube thin films. NANOSCALE 2016; 8:3232-3236. [PMID: 26792245 DOI: 10.1039/c5nr08784h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We show that the application of lateral shear force on a randomly oriented thin film of carbon nanotubes, in the dry state, causes significant reordering of the nanotubes at the film surface. This new technique of dry shear aligning is applicable to carbon nanotube thin films produced by many of the established methods.
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Affiliation(s)
- D D Tune
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
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55
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Guo Z, Chen X, Xu Y, Liu H. Enhancing the linear flow of fine granules through the addition of elongated particles. Sci Rep 2015; 5:16071. [PMID: 26551736 PMCID: PMC4638156 DOI: 10.1038/srep16071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 10/06/2015] [Indexed: 11/16/2022] Open
Abstract
Sandglasses have been used to record time for thousands of years because of their constant flow rates; however, they now are drawing attention for their substantial scientific importance and extensive industrial applications. The presence of elongated particles in a binary granular system is believed to result in undesired flow because their shape implies a larger resistance to flow. However, our experiments demonstrate that the addition of elongated particles can substantially reduce the flow fluctuation of fine granules and produce a stable linear flow similar to that in an hourglass. On the basis of experimental data and previous reports of flow dynamics, we observed that the linear flow is driven by the “needle particle effect,” including flow orientation, reduced agglomeration, and local perturbation. This phenomenon is observed in several binary granular systems, including fine granules and secondary elongated particles, which demonstrates that our simple method can be widely applied to the accurate measurement of granular flows in industry.
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Affiliation(s)
- Zhiguo Guo
- Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China.,Shanghai Engineering Research Center of Coal Gasification, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China
| | - Xueli Chen
- Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China.,Shanghai Engineering Research Center of Coal Gasification, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China
| | - Yang Xu
- Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China.,Shanghai Engineering Research Center of Coal Gasification, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China
| | - Haifeng Liu
- Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China.,Shanghai Engineering Research Center of Coal Gasification, East China University of Science and Technology, P. O. Box 272, Shanghai 200237, PR. China
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56
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Wortel G, Börzsönyi T, Somfai E, Wegner S, Szabó B, Stannarius R, van Hecke M. Heaping, secondary flows and broken symmetry in flows of elongated granular particles. SOFT MATTER 2015; 11:2570-2576. [PMID: 25679351 DOI: 10.1039/c4sm02534b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this paper we report experiments where we shear granular rods in split-bottom geometries, and find that a significant heap of height of least 40% of the filling height can form at the particle surface. We show that heaping is caused by a significant secondary flow, absent for spherical particles. Flow reversal transiently reverses the secondary flow, leading to a quick collapse and slower regeneration of the heap. We present a symmetry argument and experimental data that show that the generation of the secondary flow is driven by a misalignment of the mean particle orientation with the streamlines of the flow. This general mechanism is expected to be important in all flows of sufficiently anisometric grains.
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Affiliation(s)
- Geert Wortel
- Huygens-Kamerlingh Onnes Lab, Postbus 9504, 2300 RA Leiden, The Netherlands.
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57
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Boton M, Estrada N, Azéma E, Radjaï F. Particle alignment and clustering in sheared granular materials composed of platy particles. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2014; 37:116. [PMID: 25412821 DOI: 10.1140/epje/i2014-14116-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 09/15/2014] [Accepted: 11/03/2014] [Indexed: 06/04/2023]
Abstract
By means of molecular dynamics simulations, we investigate the texture and local ordering in sheared packings composed of cohesionless platy particles. The morphology of large packings of platy particles in quasistatic equilibrium is complex due to the combined effects of local nematic ordering of the particles and anisotropic orientations of contacts between particles. We find that particle alignment is strongly enhanced by the degree of platyness and leads to the formation of face-connected clusters of exponentially decaying size. Interestingly, due to dynamics in continuous shearing, this ordering phenomenon emerges even in systems composed of particles of very low platyness differing only slightly from spherical shape. The number of clusters is an increasing function of platyness. However, at high platyness the proportion of face-face interactions is too low to allow for their percolation throughout the system.
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Affiliation(s)
- Mauricio Boton
- Departamento de Ingeniería Civil y Ambiental - CeiBA Complex Systems Research Center, Universidad de Los Andes, Bogotá, Colombia
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58
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Szabó B, Török J, Somfai E, Wegner S, Stannarius R, Böse A, Rose G, Angenstein F, Börzsönyi T. Evolution of shear zones in granular materials. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:032205. [PMID: 25314435 DOI: 10.1103/physreve.90.032205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Indexed: 06/04/2023]
Abstract
The evolution of wide shear zones or shear bands was investigated experimentally and numerically for quasistatic dry granular flows in split bottom shear cells. We compare the behavior of materials consisting of beads, irregular grains, such as sand, and elongated particles. Shearing an initially random sample, the zone width was found to significantly decrease in the first stage of the process. The characteristic shear strain associated with this decrease is about unity and it is systematically increasing with shape anisotropy, i.e., when the grain shape changes from spherical to irregular (e.g., sand) and becomes elongated (pegs). The strongly decreasing tendency of the zone width is followed by a slight increase which is more pronounced for rodlike particles than for grains with smaller shape anisotropy (beads or irregular particles). The evolution of the zone width is connected to shear-induced packing density change and for nonspherical particles it also involves grain reorientation effects. The final zone width is significantly smaller for irregular grains than for spherical beads.
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Affiliation(s)
- Balázs Szabó
- Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
| | - János Török
- Institute of Physics, Budapest University of Technology and Economics, H-1111 Budapest, Hungary
| | - Ellák Somfai
- Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
| | - Sandra Wegner
- Otto-von-Guericke University, D-39106 Magdeburg, Germany
| | | | - Axel Böse
- Otto-von-Guericke University, D-39106 Magdeburg, Germany
| | - Georg Rose
- Otto-von-Guericke University, D-39106 Magdeburg, Germany
| | | | - Tamás Börzsönyi
- Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
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59
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Anomalous orientations of a rigid carbon nanotube in a sheared fluid. Sci Rep 2014; 4:6120. [PMID: 25134626 PMCID: PMC4137343 DOI: 10.1038/srep06120] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 07/28/2014] [Indexed: 11/08/2022] Open
Abstract
The nanoparticle orientation in fluid systems can be correlated with the rotational diffusion and is widely used to tune the physical properties of functional materials. In the current work, the controllability of the orientation of a single rigid carbon nanotube in a fluid is investigated by imposing a linear shear flow. Molecular dynamics simulations reveal three forms of anomalous behavior: (i) “Aligned orientation” when the nanotube oscillates around a particular direction which is close to the flow direction at a small angle of about 10° in the velocity-gradient plane; (ii) “Interrupted orientation” when the oscillation is interrupted by a 360° rotation now and then; (iii) “Random orientation” when 360° rotations dominate with the rotational direction coinciding with the local fluid flow direction. The orientation order is a function of the Peclet number (Pe). The results show that the correlation between Pe and the orientation order from the two-dimensional model does not apply to the three-dimensional cases, perhaps due to some anomalous behavior and cross-section effects. This work provides clear pictures of the nanoparticle movement that can be used to guide particle manipulation techniques.
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60
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Wegner S, Stannarius R, Boese A, Rose G, Szabó B, Somfai E, Börzsönyi T. Effects of grain shape on packing and dilatancy of sheared granular materials. SOFT MATTER 2014; 10:5157-67. [PMID: 24911156 DOI: 10.1039/c4sm00838c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A granular material exposed to shear shows a variety of unique phenomena: Reynolds dilatancy, positional order and orientational order effects may compete in the shear zone. We study granular packing consisting of macroscopic prolate, oblate and spherical grains and compare their behaviour. X-ray tomography is used to determine the particle positions and orientations in a cylindrical split bottom shear cell. Packing densities and the arrangements of individual particles in the shear zone are evaluated. For anisometric particles, we observe the competition of two opposite effects. On the one hand, the sheared granules are dilated, on the other hand the particles reorient and align with respect to the streamlines. Even though aligned cylinders in principle may achieve higher packing densities, this alignment compensates for the effect of dilatancy only partially. The complex rearrangements lead to a depression of the surface above the well oriented region while neighbouring parts still show the effect of dilation in the form of heaps. For grains with isotropic shapes, the surface remains rather flat. Perfect monodisperse spheres crystallize in the shear zone, whereby positional order partially overcompensates dilatancy effects. However, even slight deviations from the ideal monodisperse sphere shape inhibit crystallization.
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Affiliation(s)
- Sandra Wegner
- Otto-von-Guericke Universität Magdeburg, Institute for Experimental Physics, D-39016 Magdeburg, Germany
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61
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Xia C, Zhu K, Cao Y, Sun H, Kou B, Wang Y. X-ray tomography study of the random packing structure of ellipsoids. SOFT MATTER 2014; 10:990-996. [PMID: 24983109 DOI: 10.1039/c3sm52841c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present an X-ray tomography study for the random packing of ellipsoids. The local structure displays short-range correlations. In addition to the contact number Z, we introduce ρshell, the average contact radius of curvature for contacting neighbors, as an additional parameter to characterize the local orientational geometry. In general, the local free volume w is affected by both Z and ρshell. We believe that the particle asphericity induces a polydispersity effect to influence the packing properties. A model is introduced which explicitly maps the ellipsoid packing onto a polydispersed sphere one, and it reproduces most of the experimental observations.
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62
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Hua X, Curtis J, Hancock B, Ketterhagen W, Wassgren C. The kinematics of non-cohesive, sphero-cylindrical particles in a low-speed, vertical axis mixer. Chem Eng Sci 2013. [DOI: 10.1016/j.ces.2013.05.063] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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63
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Nahar S, Schmets A, Scarpas A, Schitter G. Temperature and thermal history dependence of the microstructure in bituminous materials. Eur Polym J 2013. [DOI: 10.1016/j.eurpolymj.2013.03.027] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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64
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Kim J, Peretti J, Lahlil K, Boilot JP, Gacoin T. Optically anisotropic thin films by shear-oriented assembly of colloidal nanorods. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:3295-3300. [PMID: 23666846 DOI: 10.1002/adma.201300594] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Indexed: 06/02/2023]
Abstract
Device-scale thin films of highly oriented (in-plane) colloidal nanorods are made available by using a simple coating process involving thixotropic rod gel suspensions. Application of this process to LaPO₄ nanorods leads to films exhibiting outstanding anisotropic optical properties, such as a remarkably large birefringence (Δn = 0.13) associated with high transparency, and sharply polarized fluorescence spectra when doped with europium.
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Affiliation(s)
- Jongwook Kim
- Laboratoire de Physique de la Matière Condensée, CNRS-Ecole Polytechnique, 91128, Palaiseau, France
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65
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Azéma E, Radjai F, Dubois F. Packings of irregular polyhedral particles: strength, structure, and effects of angularity. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:062203. [PMID: 23848667 DOI: 10.1103/physreve.87.062203] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Indexed: 06/02/2023]
Abstract
We present a systematic numerical investigation of the shear strength and structure of granular packings composed of irregular polyhedral particles. The angularity of the particles is varied by increasing the number of faces from 8 (octahedronlike shape) to 596. We find that the shear strength increases with angularity up to a maximum value and saturates as the particles become more angular (below 46 faces). At the same time, the packing fraction increases to a peak value but declines for more angular particles. We analyze the connectivity and anisotropy of the microstructure by considering both the contacts and branch vectors joining particle centers. The increase of the shear strength with angularity is shown to be due to a net increase of the fabric and force anisotropies but at higher particle angularity a rapid falloff of the fabric anisotropy is compensated by an increase of force anisotropy, leading thus to the saturation of shear strength.
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Affiliation(s)
- Emilien Azéma
- Université Montpellier 2, CNRS, LMGC, Cc 048, Place Eugène Bataillon, F-34095 Montpellier cedex 05, France.
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66
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Harth K, Kornek U, Trittel T, Strachauer U, Höme S, Will K, Stannarius R. Granular gases of rod-shaped grains in microgravity. PHYSICAL REVIEW LETTERS 2013; 110:144102. [PMID: 25166993 DOI: 10.1103/physrevlett.110.144102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Indexed: 06/03/2023]
Abstract
Granular gases are convenient model systems to investigate the statistical physics of nonequilibrium systems. In the literature, one finds numerous theoretical predictions, but only few experiments. We study a weakly excited dilute gas of rods, confined in a cuboid container in microgravity during a suborbital rocket flight. With respect to a gas of spherical grains at comparable filling fraction, the mean free path is considerably reduced. This guarantees a dominance of grain-grain collisions over grain-wall collisions. No clustering was observed, unlike in similar experiments with spherical grains. Rod positions and orientations were determined and tracked. Translational and rotational velocity distributions are non-Gaussian. Equipartition of kinetic energy between translations and rotations is violated.
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Affiliation(s)
- K Harth
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - U Kornek
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - T Trittel
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - U Strachauer
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - S Höme
- Institute of Automation Engineering, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - K Will
- Institute for Electronics, Signal Processing and Communications, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
| | - R Stannarius
- Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany
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67
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Börzsönyi T, Szabó B, Wegner S, Harth K, Török J, Somfai E, Bien T, Stannarius R. Shear-induced alignment and dynamics of elongated granular particles. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:051304. [PMID: 23214776 DOI: 10.1103/physreve.86.051304] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Indexed: 06/01/2023]
Abstract
The alignment, ordering, and rotation of elongated granular particles was studied in shear flow. The time evolution of the orientation of a large number of particles was monitored in laboratory experiments by particle tracking using optical imaging and x-ray computed tomography. The experiments were complemented by discrete element simulations. The particles develop an orientational order. In the steady state the time- and ensemble-averaged direction of the main axis of the particles encloses a small angle with the streamlines. This shear alignment angle is independent of the applied shear rate, and it decreases with increasing grain aspect ratio. At the grain level the steady state is characterized by a net rotation of the particles, as dictated by the shear flow. The distribution of particle rotational velocities was measured both in the steady state and also during the initial transients. The average rotation speed of particles with their long axis perpendicular to the shear alignment angle is larger, while shear aligned particles rotate slower. The ratio of this fast/slow rotation increases with particle aspect ratio. During the initial transient starting from an unaligned initial condition, particles having an orientation just beyond the shear alignment angle rotate opposite to the direction dictated by the shear flow.
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Affiliation(s)
- Tamás Börzsönyi
- Institute for Solid State Physics and Optics, Wigner Research Center for Physics, Hungarian Academy of Sciences, PO Box 49, H-1525 Budapest, Hungary.
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