Abstract
Granular gases are interesting multiparticle systems which, irrespective of the apparent simplicity of particle interactions, exhibit a rich scenario of so far only little understood features. We have numerically investigated a dense granular gas composed of frictional spherocylinders which are excited mechanically by lateral vibrating container walls. This study was stimulated by experiments in microgravity on parabolic flights. The formation of spatial inhomogeneities (clusters) was observed in a region near the corners of the container, about halfway from the excitation plates. The particles in the clusters show a tendency to align parallel to the container walls, seemingly increasing the stabilizing effect of friction. The simulation results provide hints that the phase difference of the vibrations of the two excitation walls might affect the cluster dynamics.
Highlights
This state can be considered as a liquid state, with colderGranular gases have been investigated numerically in numerous studies, primarily with focus on hard sphere ensembles [1, 2]
The dynamic phenomena and regime maps are known for spherical grains, corresponding results are reported, e.g., in Refs. [14,15,16,17,18]
Our simulations are motivated by the VIP-GRAN experiment performed on parabolic flights by the SPACE GRAINS team [7, 8], where we currently study clustering in ensembles of cylindrical grains
Summary
Granular gases have been investigated numerically in numerous studies, primarily with focus on hard sphere ensembles [1, 2]. For a selective and purposeful choice of experimental parameters, simulations of such ensembles in close relation to experiments are very helpful It has been shown [4,5,6, 10], that the choice of nonspherical, rod-like particles offers several advantages, viz. Collisions of non-spherical objects may be better suited to reflect the behavior of realistic, irregular grains While these advantages are beneficial in experiments, computation is considerably more complicated than for spheres [11,12,13]. We use a hybrid GPU-CPU implementation of discrete element modelling [12, 13], adapted to simulate confined systems with moving walls It solves the dynamics of a monodisperse ensemble of spherocylinders, with length and radius r, i.e. aspect ratio ζ = /2r.
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