(85b) DEM Validation Using An Annular Shear Cell

Studying the flow of granular materials is important for its impact on both industrial applications and natural phenomena.  A fundamental understanding of the flow of granular materials is lacking, and this results in difficulties in modeling and predicting their flow behavior.  The discrete element method (DEM) is often used as the "golden standard" for comparison to continuum-level theories of granular material flows due to its derivation from first-principal constructs, like contact mechanics.  In this paper, we continue our work on quantitative validation of DEM simulations using detailed measurements of simple, well-characterized flows that allow us to examine the effect of rough surfaces and rotational rates on granular flow using an annular shear cell.  Experimentally, we use digital particle tracking velocimetry (DPTV) to obtain velocity, solids fractions, and granular temperatures profiles.  Computationally, we compare the results obtained using different contact mechanics force laws to those of experimental measurements as well as perform a sensitivity analysis on device and particle geometry and different material properties employed. In previous work, we have found that an elasto-plastic normal force model is critical to obtaining accurate results as is detailed matching of both particle and system geometry, while friction model choice is found to be unimportant. Here, we examine the robustness of these observations to both particle materials properties as well as systemic variables (such as total system solids fraction).