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Granular transport in driven granular gas Noirhomme, Martial ; Opsomer, Eric ; Ludewig, François et al in European Physical Journal E -- Soft Matter (2015), 38 We numerically and theoretically investigate the behavior of a granular gas driven by asymmetric plates. The injection of energy in the dissipative system differs from one side to the opposite one. We ... [more ▼] We numerically and theoretically investigate the behavior of a granular gas driven by asymmetric plates. The injection of energy in the dissipative system differs from one side to the opposite one. We prove that the dynamical clustering which is expected for such a system is affected by the asymmetry. As a consequence, the cluster position can be fully controlled. This property could lead to various applications in the handling of granular materials in low-gravity environment. Moreover, the dynamical cluster is characterized by natural oscillations which are also captured by a model. These oscillations are mainly related to the cluster size, thus providing an original way to probe the clustering behavior. [less ▲] Detailed reference viewed: 19 (6 ULg)Bernal random loose packing through freeze-thaw cycling Ludewig, François ; Vandewalle, Nicolas ; Dorbolo, Stéphane et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015) We study the effect of freeze-thaw cycling on the packing fraction of equal spheres immersed in water. The water located between the grains experiences a dilatation during freezing and a contraction ... [more ▼] We study the effect of freeze-thaw cycling on the packing fraction of equal spheres immersed in water. The water located between the grains experiences a dilatation during freezing and a contraction during melting. After several cycles, the packing fraction converges to a particular value η∞ = 0.595 independently of its initial value η0. This behavior is well reproduced by numerical simulations. Moreover, the numerical results allow one to analyze the packing structural configuration. With a Vorono ̈ı partition analysis, we show that the piles are fully random during the whole process and are characterized by two parameters: the average Vorono ̈ı volume μv (related to the packing fractionη)andthestandarddeviationσv ofVorono ̈ıvolumes.Thefreeze-thawdrivingmodifythevolumestandard deviation σv to converge to a particular disordered state with a packing fraction corresponding to the random loose packing fraction ηBRLP obtained by Bernal during his pioneering experimental work. Therefore, freeze-thaw cycling is found to be a soft and spatially homogeneous driving method for disordered granular materials. [less ▲] Detailed reference viewed: 23 (6 ULg)Clustering and segregation in driven granular fluids Opsomer, Eric ; Vandewalle, Nicolas ; Noirhomme, Martial et al in European Physical Journal E -- Soft Matter (2014) In microgravity, the successive inelastic collisions in a granular gas can lead to a dynamical clustering of the particles. This transition depends on the filling fraction of the system, the restitution ... [more ▼] In microgravity, the successive inelastic collisions in a granular gas can lead to a dynamical clustering of the particles. This transition depends on the filling fraction of the system, the restitution of the used materials and on the size of the particles. We report simulations of driven bi-disperse gas made of small and large spheres. The size as well as the mass difference imply a strong modification in the kinematic chain of collisions and therefore alter significantly the formation of a cluster. Moreover, the different dynamical behaviors can also lead to a demixing of the system, adding a few small particles in a gas of large ones can lead to a partial clustering of the taller type. We realized a detailed phase diagram recovering the encountered regimes and developed a theoretical model predicting the possibility of dynamical clustering in binary systems. [less ▲] Detailed reference viewed: 11 (1 ULg)Dynamics of a grain-filled ball on a vibrating plate Pacheco Vazquez, Felipe ; Ludewig, François ; Dorbolo, Stéphane in Physical Review Letters (2014), 113 Detailed reference viewed: 81 (8 ULg)Bouncing dynamics of a spring Hubert, Maxime ; Ludewig, François ; Dorbolo, Stéphane et al in Physica D: Nonlinear Phenomena (2014), 272 Detailed reference viewed: 60 (24 ULg)How dynamical clustering triggers Maxwell's demon in microgravity Opsomer, Eric ; Noirhomme, Martial ; Vandewalle, Nicolas et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013), 88 In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is ... [more ▼] In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is injected into the system. By compartmentalizing the cell in several subcells of smaller volume, local clustering is triggered and the so formed dense regions act as stable traps. In this paper, molecular dynamics simulations were performed in order to reproduce the phenomenon and to analyze the formation and the stability of such traps. Depending on the total number N of particles present in the whole system, several clustering modes are encountered and a corresponding bifurcation diagram is presented. Moreover, an iterative model based on the measured particle flux F as well as a theoretical model giving the asymptotical steady states are used to validate our results. The obtained results are promising and can provide ways to manipulate grains in microgravity. [less ▲] Detailed reference viewed: 26 (8 ULg)Influence of the gravity on the discharge of a silo Dorbolo, Stéphane ; Maquet, Laurent ; Brandenbourger, Martin et al in Granular Matter (2013), 15 Detailed reference viewed: 81 (39 ULg)The role of the droplet deformations in the bouncing droplet dynamics Terwagne, Denis ; Ludewig, François ; Vandewalle, Nicolas et al in Physics of Fluids (2013), 25 Detailed reference viewed: 50 (10 ULg)Dynamical clustering in driven granular gas Opsomer, Eric ; Ludewig, François ; Vandewalle, Nicolas in Europhysics Letters [=EPL] (2012), 99 Driven granular gases present rich dynamical behaviors. Due to inelastic collisions, particles may form dense and slow regions. These clusters emerge naturally during a cooling phenomenon but another ... [more ▼] Driven granular gases present rich dynamical behaviors. Due to inelastic collisions, particles may form dense and slow regions. These clusters emerge naturally during a cooling phenomenon but another dynamical clustering is observed when the system is continuously excited. In this paper, the physical processes that trigger the transition from a granular gas to a dynamical cluster are evidenced through numerical simulations. At the granular scale, the transition is evidenced by the observation of caging effects. At the scale of the system, the transition is emphasized by density fluctuations. Physical arguments, based on relaxation times, provide an analytical prediction for the edge between dynamical regimes. [less ▲] Detailed reference viewed: 18 (4 ULg)Energetic approach of the gas-cluster transition in microgravity Opsomer, Eric ; Ludewig, François ; Vandewalle, Nicolas Poster (2012, April 03) Detailed reference viewed: 20 (2 ULg)How does an ice block assembly melt? Dorbolo, Stéphane ; Ludewig, François ; Vandewalle, Nicolas et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012) Detailed reference viewed: 40 (17 ULg)How relative humidity affects random packing experiments Vandewalle, Nicolas ; Lumay, Geoffroy ; Ludewig, François et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 85 The influence of relative humidity (RH) on the extremely slow compaction dynamics of a granular assembly has been experimentally investigated. Millimeter-sized glass beads are considered. Compaction ... [more ▼] The influence of relative humidity (RH) on the extremely slow compaction dynamics of a granular assembly has been experimentally investigated. Millimeter-sized glass beads are considered. Compaction curves are fitted by stretched exponentials with characteristic time τ and exponent δ, which are seen to be deeply affected by the moisture content. A kinetic model, taking into account both triboelectric and capillary effects, is in excellent agreement with our results. It confirms the existence of an optimal condition at a relative humidity ≈45% for minimizing cohesive interactions between glass beads. The exponent δ is seen to depend strongly on the diffusive character of grains and voids inside the packing: diffusion for cohesiveless particles and subdiffusion when cohesion plays a role. As a consequence, the RH represents a relevant parameter that should be reported for every experimental work on a slowly driven dense random packing. [less ▲] Detailed reference viewed: 37 (5 ULg)Epidemic spreading in a finite-precision BA model Ababou, Malika ; Vandewalle, Nicolas ; et al in Physica A: Statistical Mechanics and its Applications (2011) The Barabasi-Albert (BA) model with ﬁnite-precision preferential attachment is used to build a wide range of network structures. Spreading epidemics and collective dynamics are investigated on such ... [more ▼] The Barabasi-Albert (BA) model with ﬁnite-precision preferential attachment is used to build a wide range of network structures. Spreading epidemics and collective dynamics are investigated on such complex networks. Numerical simulations reveal a transition from an exponential scaling to a power law distribution of link numbers per node along with the increase of the tuning parameter ω. The collective synchronization induced by Susceptible- Infected-Recovered-Susceptible (SIRS) epidemiological process is shown to depend on the topological structure of the network. [less ▲] Detailed reference viewed: 137 (16 ULg)Influence of a reduced gravity on the volume fraction of a monolayer of spherical grains Dorbolo, Stéphane ; ; Ludewig, François et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 84 Detailed reference viewed: 44 (13 ULg)Phase transitions in vibrated granular systems in microgravity Opsomer, Eric ; Vandewalle, Nicolas ; Ludewig, François in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011) Detailed reference viewed: 45 (7 ULg)Granular gas in periodic lattice Dorbolo, Stéphane ; ; et al in European Journal of Physics (2011), 32 Detailed reference viewed: 77 (29 ULg)van der Waals cohesion in Non Smooth Contact Dynamics : application to powder mixtures Ludewig, François ; Dorbolo, Stéphane ; Boschini, Frédéric et al in Canadian Journal of Physics (2011) Detailed reference viewed: 41 (19 ULg)Compaction Dynamlics of Wet Granular Assemblies ; Lumay, Geoffroy ; Ludewig, François et al in Physical Review Letters (2010), 105 The extremely slow compaction dynamics of wet granular assemblies is studied experimentally. The cohesion, due to capillary bridges between neighboring grains, is tuned using different liquids having ... [more ▼] The extremely slow compaction dynamics of wet granular assemblies is studied experimentally. The cohesion, due to capillary bridges between neighboring grains, is tuned using different liquids having speciﬁc surface tension values. The compaction dynamics of a cohesive packing obeys an inverse logarithmic law, like most dry random packings. However, the characteristic relaxation time grows strongly with cohesion. A model, based on free volume kinetic equations and the presence of a capillary energy barrier, is able to reproduce quantitatively the experimental curves. [less ▲] Detailed reference viewed: 96 (16 ULg)Characterization of tap intensity for granular compaction Ludewig, François ; Dorbolo, Stéphane ; Vandewalle, Nicolas in Powders and Grains 2009 (2009) Detailed reference viewed: 17 (6 ULg)Bouncing trimer: a random self-propelled particle, chaos and periodical motions Dorbolo, Stéphane ; Ludewig, François ; Vandewalle, Nicolas in New Journal of Physics (2009), 11 Detailed reference viewed: 53 (19 ULg) |
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