Dynamics and rheology of superballs in planar shear flow with gravity
Phys. Rev. Fluids 10, 104306 – Published 24 October, 2025
DOI: https://doi.org/10.1103/wrbg-fpm2
Abstract
This study conducts a systematic investigation into the effects of particle shape on granular flow dynamics through discrete element method (DEM) simulations, with particular emphasis on rheological properties of superballs in plane shear with gravity. Comparative analysis reveals that superballs exhibit distinct flow characteristics relative to spherical particles, including pronounced boundary effects, increased equivalent bulk viscosity, and modified velocity profiles. A generalized rheological framework is established through the development of particle shape-dependent constitutive model that quantitatively correlates particle shape parameters with effective friction coefficient. This model incorporates a dimensionless granular temperature to account for nonlocal effects, enabling comprehensive rheological characterization across both quasistatic and inertial flow regimes. Validation through continuous simulations, achieved by implementing rheology-dependent viscosity in the Navier-Stokes equations, demonstrates excellent agreement with corresponding DEM results in predicting transient flow behavior during granular collapse. These findings establish a robust theoretical foundation for predicting flow behaviors in granular systems with complex particle geometries, providing significant advancements in the modeling and analysis of natural and industrial granular materials.
