Dynamics of granular systems

Herrmann, Hans J.; Luding, Stefan; Cafiero, R.

doi:10.1016/s0378-4371(01)00059-0

Cited by 20 publications

(14 citation statements)

References 20 publications

(29 reference statements)

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“…The predictions of this model are consequently incompatible with the experimental velocity distributions, that show important non Gaussian features already at thermal velocity scale [3,4,6]. We emphasize however that generalizations of the aforementioned heated model have been proposed [17,18]. With a convenient choice of the extra parameters introduced, one may obtain a velocity distribution close to that measured in the experiments (we will come back to this point in section 4).…”

Section: Introductionmentioning

confidence: 92%

Random inelasticity and velocity fluctuations in a driven granular gas

Barrat

Trizac

2003

Eur. Phys. J. E

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We analyze the deviations from Maxwell-Boltzmann statistics found in recent experiments studying velocity distributions in two-dimensional granular gases driven into a non-equilibrium stationary state by a strong vertical vibration. We show that in its simplest version, the "stochastic thermostat" model of heated inelastic hard spheres, contrary to what has been hitherto stated, is incompatible with the experimental data, although predicting a reminiscent high-velocity stretched-exponential behavior with an exponent 3/2. The experimental observations lead to refine a recently proposed random restitution coefficient model. Very good agreement is then found with experimental velocity distributions within this framework, which appears self-consistent and further provides relevant probes to investigate the universality of the velocity statistics.

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Section: Introductionmentioning

confidence: 92%

Random inelasticity and velocity fluctuations in a driven granular gas

Barrat

Trizac

2003

Eur. Phys. J. E

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“…The failure of Boltzmann and Enskog theories at high densities is therefore expected, even for elastic hard sphere systems. On the other hand, non-equilibrium molecular dynamics (NEMD) simulations [3,23] can, in principle, give "exact" results for driven inelastic-hard-sphere systems [24,25]. These simulations can be used to validate kinetic theories against the underlying model.…”

Section: Introductionmentioning

confidence: 99%

Collision statistics in sheared inelastic hard spheres

et al. 2009

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The dynamics of sheared inelastic-hard-sphere systems are studied using non-equilibrium molecular dynamics simulations and direct simulation Monte Carlo. In the molecular dynamics simulations LeesEdwards boundary conditions are used to impose the shear. The dimensions of the simulation box are chosen to ensure that the systems are homogeneous and that the shear is applied uniformly. Various system properties are monitored, including the one-particle velocity distribution, granular temperature, stress tensor, collision rates, and time between collisions. The one-particle velocity distribution is found to agree reasonably well with an anisotropic Gaussian distribution, with only a slight overpopulation of the high velocity tails. The velocity distribution is strongly anisotropic, especially at lower densities and lower values of the coefficient of restitution, with the largest variance in the direction of shear. The density dependence of the compressibility factor of the sheared inelastic hard sphere system is quite similar to that of elastic hard sphere fluids. As the systems become more inelastic, the glancing collisions begin to dominate more direct, head-on collisions. Examination of the distribution of the time between collisions indicates that the collisions experienced by the particles are strongly correlated in the highly inelastic systems. A comparison of the simulation data is made with DSMC simulation of the Enskog equation. Results of the kinetic model of Montanero et al. [Montanero et al., J. Fluid Mech. 389, 391 (1999)] based on the Enskog equation are also included. In general, good agreement is found for high density, weakly inelastic systems. * Electronic address: leo.lue@manchester.ac.uk 1

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“…It has been pointed out that inelastic collisions between the particles play an important role in driven granular systems and can cause size segregation[IO] and clustering [3]. In our experiments millets and mungs are free to travel between compartments A and B, and the number of them in each compartment varying all the time.…”

Section: Analysis Of Experimental Resultsmentioning

confidence: 95%