Sat, 05 Jul 2008 00:12:36 BST CiteULike: dchen shearband http://www.citeulike.org/user/dchen/tag/shearband CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2883916 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 2. (2007)</i><br /><br />The rheology of a two-dimensional granular gas under a plane shear is investigated. From the comparison among the discrete element method, the simulation of a set of hydrodynamic equation, and the analytic solution of the steady hydrodynamic equations, it is confirmed that the fluid equations derived from the kinetic theory give us accurate results even in relatively high density cases. Rheology of a granular gas under a plane shear Kuniyasu Saitoh Hisao Hayakawa doi:10.1103/PhysRevE.75.021302 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 2. (2007) 2008-06-11T22:15:13-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 75 2 APS 2007 gas grains hydrodynamics pre shear shearband http://www.citeulike.org/user/dchen/article/2883759 <i>Nature, Vol. 425, No. 6955. (2003), pp. 256-256.</i> Kinematics: Wide shear zones in granular bulk flow Denis Fenistein Martin van Hecke doi:10.1038/425256a Nature, Vol. 425, No. 6955. (2003), pp. 256-256. 2008-06-11T20:26:41-00:00 2003 Nature 425 6955 256 256 grains nature shear shearband http://www.citeulike.org/user/dchen/article/2883644 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 1. (2007)</i><br /><br />In a realistic three-dimensional setup, we simulate the slow deformation of idealized granular media composed of spheres undergoing an axisymmetric triaxial shear test. We follow the self-organization of the spontaneous strain localization process leading to a shear band and demonstrate the existence of a critical packing density inside this failure zone. The asymptotic criticality arising from the dynamic equilibrium of dilation and compaction is found to be restricted to the shear band, while the density outside of it keeps the memory of the initial packing. The critical density of the shear band depends on friction (and grain geometry) and in the limit of infinite friction it defines a specific packing state, namely the dynamic random loose packing. Critical packing in granular shear bands S Fazekas J Török J Kertész doi:10.1103/PhysRevE.75.011302 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 1. (2007) 2008-06-11T19:37:09-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 75 1 APS 2007 cool density friction grains packing pre shear shearband simulation structure http://www.citeulike.org/user/dchen/article/2883403 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 6. (2007)</i><br /><br />The shear flow of a triblock copolymer micellar solution (PEO-PPO-PEO Pluronic P84 in brine) is investigated using simultaneous rheological and velocity profile measurements in the concentric cylinder geometry. We focus on two different temperatures below and above the transition temperature Tc which was previously associated with the apparition of a stress plateau in the flow curve. (i) At T=37.0  °C<Tc, the bulk flow remains homogeneous and Newtonian-like, although significant wall slip is measured at the rotor that can be linked to an inflexion point in the flow curve. (ii) At T=39.4  °C>Tc, the stress plateau is shown to correspond to stationary shear-banded states characterized by two high shear rate bands close to the walls and a very weakly sheared central band, together with large slip velocities at the rotor. In both cases, the high shear branch of the flow curve is characterized by flow instability. Interpretations of wall slip, three-band structure, and instability are proposed in light of recent theoretical models and experiments. Wall slip, shear banding, and instability in the flow of a triblock copolymer micellar solution Sébastien Manneville Annie Colin Gilles Waton Fran\ccois Schosseler doi:10.1103/PhysRevE.75.061502 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 6. (2007) 2008-06-11T16:47:04-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 75 6 APS 2007 micelle polymer pre shear shearband http://www.citeulike.org/user/dchen/article/2881148 <i></i><br /><br />We report on an experimental study of the shear-banding phenomenon in the concentrated wormlike micellar system CTAB at 20 wt. % in D2O. Time-resolved velocity profiles are recorded using ultrasonic velocimetry simultaneously to global rheological data. Our results confirm the studies performed previously by Fischer and Callaghan [Phys. Rev. E 64, 011501 (2001)]. Time averaged velocity profiles display an unsheared “nematic gel.” In the range of applied shear rate, the flow field exhibits very fast temporal fluctuations. Suspicions for the presence of three-dimensional flow are evidenced and possible causes for a three-dimensional instability are discussed together with the coupling of wall slip to bulk dynamic. Evidence for three-dimensional unstable flows in shear-banding wormlike micelles Lydiane Bécu Domitille Anache Sébastien Manneville Annie Colin 2008-06-11T00:06:30-00:00 2007 fluctuation micelle pre shear shearband http://www.citeulike.org/user/dchen/article/2880760 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 76, No. 5. (2007)</i><br /><br />The properties of shear zones forming in slow three-dimensional granular flow are investigated. We simulate a straight version of the split-bottom shear cell. It is shown that the same type of wide shear zones is obtained in the presence as well as in the absence of gravity. We investigate the relaxation of the material toward stationary flow and analyze the stress and the velocity fields. A functional form of the widening of the shear zone inside the bulk is given. We discuss the growth of the region where the material is in the critical state. The growth of this critical zone turns out to be responsible for the initial transient of the shear zone. Shear zones in granular media: Three-dimensional contact dynamics simulation Alexander Ries Dietrich Wolf Tamás Unger doi:10.1103/PhysRevE.76.051301 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 76, No. 5. (2007) 2008-06-10T19:07:42-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 76 5 APS 2007 grains pre shear shearband simulation http://www.citeulike.org/user/dchen/article/2878302 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 1. (2008)</i><br /><br />The flow of a simple glass forming system (a 80:20 binary Lennard-Jones mixture) through a planar channel is studied via molecular dynamics simulations. The flow is driven by an external body force similar to gravity. Previous studies show that the model exhibits both a static [F. Varnik et al., J. Chem. Phys. 120, 2788 (2004)] and a dynamic [F. Varnik and O. Henrich, Phys. Rev. B 73, 174209 (2006)] yield stress in the glassy phase. These observations are corroborated by the present work, where we investigate how the presence of a yield stress may affect the system behavior in a Poiseuille-type flow geometry. In particular, we observe a blunted velocity profile across the channel: A relatively wide region in the channel center flows with a constant velocity (zero shear rate) followed by a nonlinear change of the shear rate as the walls are approached. The observed velocity gradients are compared to those obtained from the knowledge of the shear stress across the channel and the flow curves (stress versus shear rate), the latter being determined in our previous simulations of homogeneous shear flow. Furthermore, using the value of the (dynamic) yield stress known from previous simulations, we estimate the threshold body force for a complete arrest of the flow. Indeed, a blockage is observed as the imposed force falls below this threshold value. Small but finite shear rates are observed at stresses above the dynamic but below the static yield stress. We discuss the possible role of the stick-slip-like motion for this observation. Profile blunting and flow blockage in a yield-stress fluid: A molecular dynamics study F Varnik D Raabe doi:10.1103/PhysRevE.77.011504 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 1. (2008) 2008-06-09T22:44:55-00:00 2008 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 77 1 APS 2008 flow grains pre shear shearband simulation http://www.citeulike.org/user/dchen/article/2730372 <i>Physical Review Letters, Vol. 90, No. 25. (27 June 2003), 258303.</i> Local Stress Relaxation and Shear Banding in a Dry Foam under Shear Alexandre Kabla Georges Debrégeas doi:10.1103/PhysRevLett.90.258303 Physical Review Letters, Vol. 90, No. 25. (27 June 2003), 258303. 2008-04-28T16:00:58-00:00 2003 Physical Review Letters 90 25 258303 American Physical Society foam shear shearband http://www.citeulike.org/user/dchen/article/2616154 <i>Physical Review Letters, Vol. 88, No. 21. (May 2002), 218301.</i><br /><br />Magnetic-resonance-imaging rheometrical experiments show that concentrated suspensions or emulsions cannot flow steadily at a uniform rate smaller than a critical value ( γ̇ c ). As a result; a “liquid” region (sheared rapidly; i.e.; at a rate larger than γ̇ c ) and a “solid” region (static) coexist. The behavior of the fluid in the liquid region follows a simple power-law model; while the extent of the solid region increases with the degree of jamming of the material. Coexistence of Liquid and Solid Phases in Flowing Soft-Glassy Materials P Coussot JS Raynaud F Bertrand P Moucheront JP Guilbaud HT Huynh S Jarny D Lesueur doi:10.1103/PhysRevLett.88.218301 Physical Review Letters, Vol. 88, No. 21. (May 2002), 218301. 2008-03-31T13:15:36-00:00 2002 Physical Review Letters 88 21 218301 American Physical Society flow phase shearband http://www.citeulike.org/user/dchen/article/2606116 <i>Physical Review Letters, Vol. 93, No. 1. (2004)</i><br /><br />Measurements of average velocity profiles in a bubble raft subjected to slow, steady shear demonstrate the coexistence between a flowing state and a jammed state similar to that observed for three-dimensional foams and emulsions [P. Coussot et al., Phys. Rev. Lett. 88, 218301 (2002)]. For sufficiently slow shear, the flow is generated by nonlinear topological rearrangements. We report on the connection between this short-time motion of the bubbles and the long-time averages. We find that velocity profiles for individual rearrangement events fluctuate, but a smooth, average velocity is reached after averaging over only a relatively few events. Velocity Profiles in Slowly Sheared Bubble Rafts John Lauridsen Gregory Chanan Michael Dennin doi:10.1103/PhysRevLett.93.018303 Physical Review Letters, Vol. 93, No. 1. (2004) 2008-03-28T12:36:40-00:00 2004 Physical Review Letters 93 1 APS bubbles shear shearband http://www.citeulike.org/user/dchen/article/2719234 <i>Physical Review Letters, Vol. 89, No. 24. (25 November 2002), 248304.</i> Theory of Nonlinear Rheology and Yielding of Dense Colloidal Suspensions Matthias Fuchs Michael Cates doi:10.1103/PhysRevLett.89.248304 Physical Review Letters, Vol. 89, No. 24. (25 November 2002), 248304. 2008-04-25T18:40:12-00:00 2002 Physical Review Letters 89 24 248304 American Physical Society microrheology shear shearband http://www.citeulike.org/user/dchen/article/2670772 <i>Nature, Vol. 367, No. 6463. (10 February 1994), pp. 541-543.</i> Deformation-induced nanocrystal formation in shear bands of amorphous alloys H Chen Y He GJ Shiflet SJ Poon doi:10.1038/367541a0 Nature, Vol. 367, No. 6463. (10 February 1994), pp. 541-543. 2008-04-14T22:43:53-00:00 1994 Nature 367 6463 541 543 application shear shearband