Microscopic two-dimensional lattice model of dimer granular compaction with friction (original) (raw)
Related papers
A microscopic 2D lattice model of dimer granular compaction with friction
Physical Review E, 2002
We study by Monte Carlo simulation the compaction dynamics of hard dimers in 2D under the action of gravity, subjected to vertical and horizontal shaking, considering also the case in which a friction force acts for horizontal displacements of the dimers. These forces are modeled by introducing effective probabilities for all kinds of moves of the particles. We analyze the
Why shape matters in granular compaction
Journal of Physics A: Mathematical and …, 2003
We present a stochastic model of dynamically interacting grains in one dimension, in the presence of a low vibrational intensity, to investigate the effect of shape on the statics and dynamics of the compaction process. Regularity and irregularity in grain shapes are shown to be centrally important in determining the statics of close-packing states, as well as the nature of zero-and low-temperature dynamics in this columnar model.
Compaction of granular systems
World Scientific Lecture Notes in Complex Systems, 2007
When submitted to gentle mechanical taps, a granular packing slowly compacts until it reaches a stationary state that depends on the tap characteristics. This phenomenon, granular compaction, reveals part of the complex nature of granular dynamics. Here, we recall some experimental results on granular compaction and show that, under certain circumstances, order appears in these systems. Investigations on that crystallization are reported.
Coarsening and Slow Dynamics in Granular Compaction
Physical Review Letters, 2001
We address the problem of the microscopic reorganization of a granular medium under a compaction process in the framework of Tetris-like models. We point out the existence of regions of spatial organization which we call domains, and study their time evolution. It turns out that after an initial transient, most of the activity of the system is concentrated on the boundaries between domains. One can then describe the compaction phenomenon as a coarsening process for the domains, and a progressive reduction of domain boundaries. We discuss the link between the coarsening process and the slow dynamics in the framework of a model of active walkers on active substrates.
Slow relaxation and compaction of granular systems
Nature Materials, 2005
nature materials | VOL 4 | FEBRUARY 2005 | www.nature.com/naturematerials 121 Slow relaxation and compaction of granular systems Granular materials are of substantial importance in many industrial and natural processes, yet their complex behaviours, ranging from mechanical properties of static packing to their dynamics, rheology and instabilities, are still poorly understood. Here we focus on the dynamics of compaction and its 'jamming' phenomena, outlining recent statistical mechanics approaches to describe it and their deep correspondence with thermal systems such as glass formers. In fact, granular media are often presented as ideal systems for studying complex relaxation towards equilibrium. Granular compaction is defi ned as an increase of the bulk density of a granular medium submitted to mechanical perturbation. This phenomenon, relevant in many industrial processes and widely studied by the soil mechanics community, is simple enough to be fully investigated and yet reveals all the complex nature of granular dynamics, attracting considerable attention in a broad range of disciplines ranging from chemical to physical sciences.
Physical Review Letters, 2005
We present an original experimental study of the compaction dynamics for two-dimensional granular systems. Compaction dynamics is measured at three different scales: the macroscopic scale through the normalized packing fraction, the mesoscopic scale through the normalized fraction of hexagonal domains in the system, and the microscopic scale through the grain mobility . Moreover, the hexagonal domains are found to obey a growth process dominated by the displacement of domain boundaries. A global picture of compaction dynamics relevant at each scale is proposed.
Granular Dynamics in Compaction and Stress Relaxation
Physical Review Letters, 2005
Elastic and dissipative properties of granular assemblies under uniaxial compression are studied both experimentally and by numerical simulations. Following a novel compaction procedure at varying oscillatory pressures, the stress response to a step-strain reveals an exponential relaxation followed by a slow logarithmic decay. Simulations indicate that the latter arises from the coupling between damping and collective grain motion predominantly through sliding. We characterize an analogous "glass transition" for packed grains, below which the system shows aging in time-dependent sliding correlation functions.
Compaction of anisotropic granular materials: Experiments and simulations
Physical Review E, 2004
We perform numerical simulation of a lattice model for the compaction of a granular material based on the idea of reversible random sequential adsorption. Reversible random sequential adsorption of objects of various shapes on a two−dimensional triangular lattice is studied numerically by means of Monte Carlo simulations. The growth of the coverage ρ(t) above the jamming limit to its steady−state value ρ ∞ is described by a pattern ρ (t) = ρ ∞ − ∆ρE β [−(t/τ) β ], where E β denotes the Mittag−Leffler function of order β ∈ (0, 1). For the first time, the parameter τ is found to decay with the desorption probability P − according to a power law τ = A P − −γ . Exponent γ is the same for all shapes, γ = 1.29 ± 0.01, but parameter A depends only on the order of symmetry axis of the shape. Finally, we present the possible relevance of the model to the compaction of granular objects of various shapes.
Compaction, Crystallization and Dynamics in Granular Systems
2002
We study experimentally a granular system composed of monodisperse ball bearings under vertical vibrations. Different container geometries are used in order to investigate the effects of boundaries on compaction and crystallization. We obtain volume fraction from random loose packing (.58) up to near hexagonal close packing (.74). We also study the dynamics of crystallization and observe the effects of annealing.