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This discussion explores the role of friction and shear stress in the jamming transition, investigating topics such as viscosity, shear banding, and hysteresis in various experimental and simulation scenarios.
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The Role of Friction and Shear stress in the Jamming Transition Antonio Coniglio Discussion Peter Schall University of Amsterdam
h = s v / l shear z No friction, applied shear stress Viscosity h G Newtonian behavior ? . s= hg • System still homogeneous ? • Shear banding ? Protocol
No friction, applied shear stress Experiments • Grains density-matched (no sedimentation) f>0.62 stress f<0.62 strain A. Fall and D. Bonn (unpublished)
No friction, applied shear stress Experiments • 2D foam
16 d x 16 d F y z 8d No friction, applied shear stress Hysteresis 16 x 16 x 8 = 2048 particles How reliable is fc ? O‘Hern et al. 2003
16 d x 16 d F y z 8d No friction, applied shear stress Hysteresis 16 x 16 x 8 = 2048 particles Is fc a good measure ? Confining pressure p Particle overlap d d
No friction, applied shear stress • Model: motion in energy landscape W(x) Crystal potential Jamming : general for solids, crystalline and amorphous systems
Nature 2001 Science 2003
Frictional particles Simulations at V = const but particles want to dilate ... Behavior at p = const ?
Frictional particles Support simple scenario of dilation ?
Frictional particles Experimental examples ? Relation with “Shear thickening“? (Suspensions under rapid shear, e.g. cornstarch, bullet-proof wests) Constant volume or pressure ? Constant pressure: Laplace pressure that holds particles in suspension