Absorbing State Phase Transition in Dense Suspensions of Non-Spherical Particles

At low Reynolds numbers, hydrodynamic reversibility is a hallmark of Stokesian flows. However, suspensions under oscillatory shear can undergo absorbing phase transitions, marked by a shift from reversible to irreversible dynamics. While this transition and its critical scaling are well-studied for spherical particles, the impact of particle shape and orientation on dense suspension dynamics remains largely unexplored. Non-spherical particles introduce orientational degrees of freedom that can dynamically alter the onset and nature of absorbing states. Here, we employ discrete element method (DEM) simulations to study dense suspensions of non-spherical particles with varying aspect ratios, utilizing triaxial periodic boundary conditions to eliminate wall effects that were present in previous studies. We systematically examine how orientational dynamics and particle geometry influence the critical strain amplitude and the absorbing phase transition, in contrast to the known behavior for spheres. Our results unveil orientation-driven pathways to irreversibility, with implications for universality classes in nonequilibrium phase transitions.