Directional shear jamming of frictionless ellipses

In this work we study shear reversals of dense non-Brownian suspensions composed of cohesionless elliptical particles. By numerical simulations, we show that a new fragility appears for frictionless ellipses in the flowing states, where particles can flow indefinitely in one direction at applied shear stresses but shear jam in the other direction upon shear stress reversal. This new fragility, absent in the isotropic particle case, is linked to the directional order of the elongated particles at steady shear and its reorientation at shear stress reversal, which forces the suspensions to pass through a more disordered state with an increased number of contacts in which it might get arrested.

Automated summary

In this study, we found a new fragility in frictionless ellipses suspensions during shear reversals, where particles can flow indefinitely in one direction but jam in the other direction. This new fragility is related to the directional order of elongated particles at steady shear and its reorientation at shear stress reversal, leading to a more disordered state with an increased number of contacts and possible arrest.