Characterization of the energy bursts in vibrated shallow granular systems

Abstract

We study the recently reported energy bursts that take place in a granular system confined to a vertically vibrated shallow box containing two types of grains of equal size but different mass (Rivas in Phys Rev Lett 106:088001-1-088001-4, 2011). In a quasi one dimensional configuration, it is possible to characterize the propagating fronts. The rapid expansion and the subsequent compression of the energy bursts take place at roughly constant velocities. The expansion velocity is 40 times larger than the compression velocity. Starting from an initially segregated configuration it is possible to determine the instants at which the energy bursts begin and the mechanisms that trigger them. Two mechanisms are identified: an oblique collision of a heavy grain with a light one in contact with one of the horizontal walls and a slow destabilization produced by light grains that are surrounded by heavy ones.

Nonequilibrium steady states, coexistence, and criticality in driven quasi-two-dimensional granular matter

“…Multiple samples have been aligned and averaged over coherently, see main text. The black straight lines show exponential fits of the maxima of h(x) to Eq (12)…”

Ballistic propagation of density correlations and excess wall forces in quenched granular media

“…Instead, a physical interpretation of v E could be provided by the following possible origin of the correlations, which-in the case of heating-is similar to bursts caused by collisions of heavy particles reported in Ref. [21]. Upon heating (weak cooling), particles are accelerated (decelerated) in z-direction by the oscillating plates to a velocity ∝ A F ω.…”

“…Cooling through inelastic dissipation takes place in every collision. Heating of the horizontal directions, on the other hand, only occurs, if a particle has been accelerated by the oscillating plates and then transfers its energy to horizontal motion in a particle-particle collision as has been demonstrated for steady state fluctuations in a setup with particles of differing masses [20,21]. Moderate quenches constitute only weak disturbances of the steady state where the described asymmetry plays only a minor role.…”

“…In particular, the parameter space for formation of regular lattices, fluids and coexistence thereof [3][4][5][6][7][8][9][10] bears analogy to the corresponding 2D equilibrium system [11]. However several properties reveal the nonequilibrium nature of the steady states, such as inelastic collapse at the bottom of the container [12][13][14][15], inhomogeneous granular temperatures [3,16], non-Gaussian velocity distributions [17][18][19], segregation of mixtures [8,20,21], and inelastic hydrodynamic modes [22].…”

Demixing of active particles in the presence of external fields

“…Multicomponent systems may demix dynamic when the response of distinct species to external fields differ significantly [1][2][3][4][5][6][7][8][9][10]. Typical examples are mixtures of colloidal particles with different electrophoretic mobilities in the presence of an external field [4,7] or granular mixtures of particles with different masses on vibrating plates [8,11].…”