题   目：Jamming And Dynamics Of Granular Materials

报 告 人：Prof. Bob Behringer

单    位：美国杜克大学物理系、非线性与复杂系统研究中心（Department Of Physics And Center For Nonlinear And  Complex Systems, Duke University）

地    点：岩土楼201室

时    间：2013年7月30日(周二)    上午9:30-10:30

联 系 人: 黄雨 教授

报告人简介：

Prof. Bob Behringer Is James. B Duke Professor Of Physics, Duke University. His Researches Fundamental Aspects Of Granular And Fluid Flows. Various Aspects Of His Work Are Supported By The NSF, By NASA, By ARO, By DARPA, By DTRA And By IFPRI. Prof. Bob Behringer Has Published Over 200 Journal Articles. He Is Editor Of International Journal: Granular Matter (Springer-Verlag), Nonlinear Science Today (Springer-Verlag), Physics Of Fluids Guest Editor, AIP Journal Chaos Issue On Granular Flow. He Is Also Reviewer For Nature, Science, Physical Review Letters, Euro Physics Letters, Physical Review B, Physical Review E, Physics Of Fluid Et Al.

报告摘要：

This Talk Will Consider The Near-Jamming Behavior Of Granular Systems Consisting Of Frictional Particles.  We Have Recently Shown That There Exists A Range Of Packing Fractions For Which It Is Possible To Start From Zero Stress States, And By Applying Shear Strain, Traverse A Regime Of Fragile States, Ultimately Arriving At A Jammed State. These Results Have Been Obtained By Using Photoelastic Particles, Which Allow Detailed Force And Contact Information, And From Several Different Kinds Of Experiments.  The Largest Density, Phi_J, For Which This Behavior Applies Is Comparable To The Jamming Density Of Frictionless Disks, And The Lowest Density For Which This Occurs, Phi_S, May Be Tied To The Random Loose Packing Density.  Shear-Jammed States Are Characterized By Anisotropy In Various Quantities Such As The Stress, The  Contact Fabric, And In General, The Force Networks.  Shear Jamming Is Of Particular Interest For Granular Dynamics, Since Many Slow Granular Shear Flows Occur Near This Regime, And The Arrest Of Flow Occurs Due To Shear Jamming, Not To Isotropic Jamming.  For Example, Couette Flow, Flows In Shear Bands, And Flows In Hoppers May All Be Influenced By Shear Jamming.

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