Title: Steady Granular Flow: Continuum Theory, Simulation, and Computational Challenges

Author (Invited): Ken Kamrin, Harvard

Abstract:

This talk constructs and tests a continuum model for dense granular matter, which can be used to predict the stress and velocity profiles in well-developed flows. Recent models for granular elasticity (Jiang and Liu 2003) and rate-sensitive plastic flow (Jop et al. 2006) are reformulated and combined into one universal elasto-plastic law, capable of determining flowing regions and stagnant zones simultaneously in any arbitrary 3D flow geometry. The model is numerically implemented as a VUMAT in ABAQUS/Explicit, and results are directly compared to experiments and discrete particle simulations in several inhomogeneous flow geometries. We also provide preliminary arguments for how to enhance the description using non-local quantities, and give examples to demonstrate the benefits of this approach. Lastly, we discuss computational issues that arise when simulating the granular elasto-plastic model (or related solid laws) to the point of steady flow. On this front, a technique is introduced to perform solid simulation on a fixed finite-difference grid, with potential simplify the modeling of highly deforming solid-like materials among other applications.