**Title:** Force-controlled walls and their application for shear tester simulations

**Presenter:** Andreas Aigner

**Affiliation:** Johannes Kepler University Linz

**Abstract:** The simulation of very dense particle regimes such as moving or fluidized beds requires a
well determined coefficient of friction, which characterizes the inter-particle friction
force. Starting from rough guide values available in the literature, we determine the exact
parameters by fitting numerical simulations to experimental measurements of a simplified
Jenike shear tester.

The open-source, discrete-element-method code LIGGGHTS is capable to model com- plex geometries built of triangulated meshes. In addition to preloading the bulk solid in the shear cell by a required constant principal stress, a new wall type is enhanced by a controller prescribing the wall motion.

A comprehensive sensitivity study shows that the results are nearly insensitive to the spa- tial dimensions of the shear tester as well as all other material parameters. Therefore, this set-up is applicable to determine the coefficient of friction.

Finally, we calculate the coefficient of friction of glass beads showing very good agree- ment with literature data and in-house experiments. Hence, this procedure can be used to deduce material parameters for the numerical simulation of dense granular flows.