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Mach cone in a shallow granular fluid
(Georgia Institute of Technology, 2004-12-23)
We study the V-shaped wake (Mach cone) formed by a cylindrical rod moving through a thin, vertically vibrated granular layer. The wake, analogous to a shock (hydraulic jump) in shallow water, appears for rod velocities vR ...
Noise, coherent fluctuations, and the onset of order in an oscillated granular fluid
(Georgia Institute of Technology, 2004-04-30)
We study fluctuations in a vertically oscillated layer of grains below the critical acceleration for the onset of ordered standing waves. As onset is approached, transient disordered waves with a characteristic length scale ...
Phase bubbles and spatiotemporal chaos in granular patterns
(Georgia Institute of Technology, 2001-12-04)
We use inelastic hard sphere molecular dynamics simulations and laboratory experiments to study patterns in vertically oscillated granular layers. The simulations and experiments reveal that phase bubbles spontaneously ...
Signatures of glass formation in a fluidized bed of hard spheres
(Georgia Institute of Technology, 2006-04-14)
We demonstrate that a fluidized bed of hard spheres during defluidization displays properties associated with formation of a glass. The final state is rate dependent, and as this state is approached, the bed exhibits ...
Kink-induced transport and segregation in oscillated granular layers
(Georgia Institute of Technology, 2003-09-26)
We use experiments and molecular dynamics simulations of vertically oscillated granular layers to study horizontal particle segregation induced by a kink (a boundary between domains oscillating out of phase). Counterrotating ...
Lattice dynamics and melting of a nonequilibrium pattern
(Georgia Institute of Technology, 2003-03-14)
We present a new description of nonequilibrium square patterns as a harmonically coupled crystal lattice. In a vertically oscillating granular layer, different transverse normal modes of the granular square-lattice pattern ...
Dynamics of drag and force distributions for projectile impact in a granular medium
(Georgia Institute of Technology, 2004-05-14)
Our experiments and molecular dynamics simulations on a projectile penetrating a two-dimensional granular medium reveal that the mean deceleration of the projectile is constant and proportional to the impact velocity. Thus, ...
Persistent holes in a fluid
(Georgia Institute of Technology, 2004-05-07)
We observe stable holes in a vertically oscillated 0.5 cm deep aqueous suspension of cornstarch. Holes appear only if a finite perturbation is applied to the layer for accelerations α above 10g. Holes are circular and ...
Stationary state volume fluctuations in a granular medium
(Georgia Institute of Technology, 2005-03-30)
A statistical description of static granular material requires ergodic sampling of the phase space spanned by the different configurations of the particles. We periodically fluidize a column of glass beads and find that ...
Crucial role of sidewalls in velocity distributions in quasi-two-dimensional granular gases
(Georgia Institute of Technology, 2004-10-19)
Our experiments and three-dimensional molecular dynamics simulations of particles confined to a vertical monolayer by closely spaced frictional walls (sidewalls) yield velocity distributions with non-Gaussian tails and a ...