Collective granular dynamics in a shaken container at low gravity conditions

Abstract

Abstract. We investigate the collective dissipative behavior of a model granular material (steel beads) when subjected to vibration. To this end, we study the attenuation of the amplitude of an oscillating leaf spring whose free end carries a rectangular box partly filled with granulate. To eliminate the perturbing influence of gravity, the experiment was performed under conditions of microgravity during parabolic flights. Different regimes of excitation could be distinguished, namely, a gas-like state of disordered particle motion and a state where the particles slosh back and forth between the container walls in a collective way, referred to as collect-and-collide regime. For the latter regime, we provide an expression for the container size leading to maximal dissipation of energy, that also marks the transition to the gas like regime. Also for systems driven at fixed amplitude and frequency, we find both the gas regime and the collect-and-collide regime resulting in similar dissipative behavior as in the case of the attenuating vibration.

Absence of Subharmonic Response in Vibrated Granular Systems under Microgravity Conditions

“…2). Although the single-particle model explained experiments up to quantitative agreement [26][27][28]50], the existence of subharmonic solutions of Eq. (1) contradicts previous results: In hundreds of single experiments and in numerical simulations [24,25], no sign of subharmonic response became apparent.…”

Three-dimensional (3D) experimental realization and observation of a granular gas in microgravity

“…Parabolic flights are useful for 3D measurements with additional stabilization of the gas (Sperl, private comm. ) and for experiments at large excitation amplitudes (Sack et al, 2013; Kollmer et al, 2013). Some experiments have also been performed with 2D gases (Yanpei et al, 2011;Tatsumi et al, 2009;Grasselli et al, 2009), where low gravity reduces friction with the container walls.…”

“…Special care has to be taken during the preparation of the experiment and the data analysis. Most of the previous experiments in reduced gravitation dealt with spherical grains, and often with small ensembles and/or two-dimensional (2D) geometries (Falcon et al, 1999;Falcon et al, 2006;Hou et al, 2008;Yanpei et al, 2011;Tatsumi et al, 2009;Grasselli et al, 2009;Kollmer et al, 2013;Heißelmann et al, 2010). In the latter case, the interactions with walls or confining potentials may dominate over the intrinsic particle-particle effects.…”

Cluster dynamics in dense granular gases of rod-like particles

“…The dynamic phenomena and regime maps are known for spherical grains, corresponding results are reported, e.g., in Refs. [14][15][16][17][18]. For rods, we expect a more complex behaviour and the actual regimes are a priori unknown.…”