The Jamming Transition in Granular Systems

TL;DR

This paper experimentally confirms the predicted jamming transition in granular systems, showing a discontinuous increase in contact number and power-law behavior of pressure and contact number above the critical volume fraction, aligning with simulations and theory.

Contribution

It provides experimental validation of the jamming transition predictions, including contact number and pressure behavior, previously only simulated or theoretically proposed.

Findings

Discontinuous jump in contact number at critical volume fraction

Power-law increase of pressure and contact number above critical point

Agreement with simulation and mean-field theory predictions

Abstract

Recent simulations have predicted that near jamming for collections of spherical particles, there will be a discontinuous increase in the mean contact number, Z, at a critical volume fraction, phi_c. Above phi_c, Z and the pressure, P are predicted to increase as power laws in phi-phi_c. In experiments using photoelastic disks we corroborate a rapid increase in Z at phi_c and power-law behavior above phi_c for Z and P. Specifically we find power-law increase as a function of phi-phi_c for Z-Z_c with an exponent beta around 0.5, and for P with an exponent psi around 1.1. These exponents are in good agreement with simulations. We also find reasonable agreement with a recent mean-field theory for frictionless particles.