AUTHOR=Marks Benjy , Sandnes Bjørnar , Dumazer Guillaume , Eriksen Jon A. , Måløy Knut J. TITLE=Compaction of granular material inside confined geometries JOURNAL=Frontiers in Physics VOLUME=3 YEAR=2015 URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2015.00041 DOI=10.3389/fphy.2015.00041 ISSN=2296-424X ABSTRACT=

In both nature and engineering, loosely packed granular materials are often compacted inside confined geometries. Here, we explore such behavior in a quasi-two dimensional geometry, where parallel rigid walls provide the confinement. We use the discrete element method to investigate the stress distribution developed within the granular packing as a result of compaction due to the displacement of a rigid piston. We observe that the stress within the packing increases exponentially with the length of accumulated grains, and show an extension to current analytic models which fits the measured stress. The micromechanical behavior is studied for a range of system parameters, and the limitations of existing analytic models are described. In particular, we show the smallest sized systems which can be treated using existing models. Additionally, the effects of increasing piston rate, and variations of the initial packing fraction, are described.