Shear localization and wall friction in confined dense granular flows

Journal of Fluid Mechanics - Tập 849 - Trang 395-418 - 2018
Riccardo Artoni1, Alberto Soligo1, Jean‐Marc Paul1, Patrick Richard1
1IFSTTAR/MAST/GPEM - Granulats et Procédés d'Elaboration des Matériaux (Centre de Nantes Route de Bouaye - BP 4129 44341 Bouguenais Cedex - France)

Tóm tắt

In this work, we discuss experiments and discrete element simulations of wall-bounded shear flows of slightly polydisperse spheres under gravity. Experiments were performed in an annular shear cell in which the bottom bumpy wall rotates at fixed velocity, while a pressure is applied at the top bumpy wall. The coaxial cylinders delimiting the flow are flat, frictional and transparent, allowing visualization of the flow. Velocity profiles were obtained by particle image velocimetry, and are characterized by an exponential profile, the decay length of which depends on the applied load, but not on the wall velocity. A force sensor was installed at different vertical positions on the outer sidewall in order to measure wall forces. The effective streamwise and transverse wall friction coefficients were thus estimated, showing wall friction weakening in creep zones. In order to better understand these results, contact dynamics simulations were carried out in a simplified configuration (Artoni & Richard, Phys. Rev. Lett., vol. 115 (15), 2015, 158001). In this case, profiting from the possibility of varying the particle–wall friction coefficient, different flow regimes were observed. In particular, shear can either be localized (1) at the bottom or (2) at the top of the shear cell, or (3) it can be quite evenly distributed in the vertical direction. Through an averaging technique that explicitly takes into account gradient effects (Artoni & Richard, Phys. Rev. E, vol. 91 (3), 2015, 032202), relevant, coarse-grained, continuum fields (solid fraction, velocity, stresses, velocity fluctuations) were obtained. They allow a discussion of the relevance of velocity fluctuations (i.e. granular temperature) for describing non-locality in granular flow. The case of solid-like fluctuations is also addressed. Finally, a simplified stress analysis is devoted to explain the emergence of complex shear localization patterns by the heterogeneity of effective bulk friction, which is due to the joint effect of gravity and wall friction.

Từ khóa


Tài liệu tham khảo

10.1038/35019032

10.1103/PhysRevLett.115.158001

10.1007/s10035-012-0317-4

10.1103/PhysRevLett.98.018301

10.1007/s40571-015-0087-y

10.1016/j.crme.2007.08.005

Zhang, 2017, Microscopic description of the granular fluidity field in nonlocal flow modeling, Phys. Rev. Lett., 118

10.1051/epjconf/201714001006

Ben Aïm, 1968, La coordinance des empilements désordonnés de sphères. Application aux mélanges binaires de sphères, Powder Technol., 2, 1, 10.1016/0032-5910(68)80027-0

10.1017/S0022112008000700

10.1007/978-3-7091-2624-0

Brodu, 2013, Shallow granular flows down flat frictional channels: steady flows and longitudinal vortices, Phys. Rev. E, 87

10.1038/nature03805

10.1017/S0022112005005987

Pouliquen, 2006, Proceedings of Powders and Grains 2005

10.1002/grl.50311

10.1039/C2SM27122B

Golick, 2009, Mixing and segregation rates in sheared granular materials, Phys. Rev. E, 80

10.1063/1.4983049

10.1209/0295-5075/83/64003

Kamrin, 2012, Nonlocal constitutive relation for steady granular flow, Phys. Rev. Lett., 108

2004, On dense granular flows, Eur. Phys. J. E, 14, 341

10.1007/s10035-012-0313-8

10.1209/epl/i2003-00156-5

10.1007/s100510050979

Camenen, 2012, Effect of confinement on dense packings of rigid frictionless spheres and polyhedra, Phys. Rev. E, 86

10.1103/PhysRevLett.101.248002

Artoni, 2015a, Average balance equations, scale dependence, and energy cascade for granular materials, Phys. Rev. E, 91

10.1016/S0045-7825(98)00383-1

10.1209/0295-5075/109/24002

10.1038/ncomms10630

10.1017/jfm.2015.109

Métayer, 2010, Electrically induced tunable cohesion in granular systems, J. Stat. Mech., 2010

10.1007/s40571-016-0143-2

10.1103/PhysRevLett.91.264301

10.1016/j.cam.2003.05.019

10.1103/PhysRevLett.111.148301

10.1038/157584b0

10.1039/C4SM01838A

10.1103/PhysRevLett.111.238301

Ananda, 2008, Kinematics and statistics of dense, slow granular flow through vertical channels, J. Fluid Mech., 610, 69, 10.1017/S0022112008002358

10.1209/0295-5075/80/34004

10.1016/0032-5910(80)87014-8

10.1209/0295-5075/94/54005

de Richter, 2010, Experimental evidence of ageing and slow restoration of the weak-contact configuration in tilted 3D granular packings, J. Stat. Mech., 2010

10.1007/s10035-016-0671-8

Crassous, 2008, Experimental study of a creeping granular flow at very low velocity, J. Stat. Mech. Theor. Exp., 2008

10.1103/PhysRevLett.77.274

10.1680/geot.1996.46.3.529

10.1209/epl/i2004-10228-0

10.1007/s10035-013-0401-4

10.1016/S0020-7225(96)00094-8

10.1017/S0022112084001166

10.1051/epjconf/201714011015

10.1103/PhysRevLett.108.238002

10.1063/1.4812809

Artoni, 2009, Effective boundary conditions for dense granular flows, Phys. Rev. E, 79

10.1016/S0010-4655(99)00332-X

Thông tin
Thông tin xuất bản

Journal of Fluid Mechanics

Tập 849

395-418

Thông tin tác giả