Comparison of compression vs pure shearing for a simple model of athermal frictionless disks in suspension

Using a simplified model for a non-Brownian suspension, we numerically study the response of athermal, overdamped, frictionless disks in two dimensions to isotropic and uniaxial compression, as well as to pure shearing, all at finite constant strain rates $\dot\epsilon$. We show that isotropic and uniaxial compression result in the same jamming packing fraction $\phi_J$, while pure shear induced jamming occurs at a slightly higher $\phi_J^*$, consistent with that found previously for simple shearing. A critical scaling analysis of pure shearing gives critical exponents consistent with those previously found for both isotropic compression and simple shearing. Using orientational order parameters for contact bond directions, we compare the anisotropy of the force and contact networks. We find that the main difference between uniaxial compression and pure shearing is given by the relative magnitude of the isotropic to nematic terms. Higher orientational moments are similar in the two cases.Comment: 15 pages, 18 figure