Extended event driven molecular dynamics for simulating dense granular matter

TL;DR

This paper introduces an efficient numerical method for simulating dense granular media by extending the inelastic hard sphere model to include frozen states, enabling better handling of static regions and dynamic coexistence.

Contribution

The paper presents a novel extension to the IHS model that allows particles to switch between frozen and normal states, improving simulation efficiency and stability in complex granular systems.

Findings

Simulations match experimental results for static and dynamic granular systems.

The new method is significantly more efficient than traditional event-driven approaches.

It overcomes limitations related to static limit in standard IHS models.

Abstract

A new numerical method is presented to efficiently simulate the inelastic hard sphere (IHS) model for granular media, when fluid and frozen regions coexist in the presence of gravity. The IHS model is extended by allowing particles to change their dynamics into either a frozen state or back to the normal collisional state, while computing the dynamics only for the particles in the normal state. Careful criteria, local in time and space, are designed such that particles become frozen only at mechanically stable positions. The homogeneous deposition over a static surface and the dynamics of a rotating drum are studied as test cases. The simulations agree with previous experimental results. The model is much more efficient than the usual event driven method and allows to overcome some of the difficulties of the standard IHS model, such as the existence of a static limit.