References of "Vandewalle, Nicolas"
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See detailDynamical clustering in driven granular gas
Opsomer, Eric ULg; Ludewig, François ULg; Vandewalle, Nicolas ULg

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 ▲]

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See detailMeasuring the flowing properties of powders and grains
Lumay, Geoffroy ULg; Boschini, Frédéric ULg; traina, Karl et al

in Powder Technology (2012), 224

A granular material is a complex system which exhibits non-trivial transitions between the static, the quasi-static and the dynamical states. Indeed, an assembly of grains can behave like a solid or a ... [more ▼]

A granular material is a complex system which exhibits non-trivial transitions between the static, the quasi-static and the dynamical states. Indeed, an assembly of grains can behave like a solid or a fluid according to the applied stress. In between solid and fluid granular states, very slow dynamics are observed. When a complete macroscopic characterization of a powder is needed, all these granular states have to be precisely analyzed. In this paper, we show how three measurement techniques can be used to measure the physical properties of a powder. The measurements are based on classical tests modified to meet the recent fundamental researches on granular materials. The static properties of the powder are analyzed through the shape of a heap. The quasi-static behavior is studied with the analysis of the compaction dynamics. Finally, the dynamical regime is monitored through the flow in a rotating drum. In order to illustrate how these measurements can be used in practical cases, analyses are performed with three types of granular materials: silicon carbide abrasives, flours and rice. These selected materials allow to show the influence of the different parameters (grain size, grain size distribution, grain shape) on the macroscopic properties of the assembly. Moreover, these studies show the pertinence of the parameters obtained with the proposed techniques for the rheological characterization of powders and grains. [less ▲]

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See detailDissipation in quasistatically sheared wet and dry sand under confinement
Fiscina, J.E.; Pakpour, M.; Fall, A. et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 86

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See detailSculpting sandcastles grain by grain: Self-assembled sand towers
Pacheco Vazquez, Felipe ULg; Moreau, Florian ULg; Vandewalle, Nicolas ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 86

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See detailbouncing of polymeric droplets on liquid interfaces
gier, stephan; Dorbolo, Stéphane ULg; Terwagne, Denis ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 86

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See detailSymmetry breaking in a few-body system with magnetocapillary interactions
Vandewalle, Nicolas ULg; Clermont, Lionel; Terwagne, Denis et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 85

We have experimentally investigated the interactions between floating magnetic spheres which are submitted to a vertical magnetic field, ensuring a tunable repulsion, while capillary forces induce ... [more ▼]

We have experimentally investigated the interactions between floating magnetic spheres which are submitted to a vertical magnetic field, ensuring a tunable repulsion, while capillary forces induce attraction. We emphasize the complex arrangements of floating bodies. The equilibrium distance between particles exhibits hysteresis when the applied magnetic field is modified. Irreversible processes are evidenced. Symmetry breaking is also found for three identical floating bodies when the strength of the magnetic repulsion is tuned. We propose a Dejarguin-Landau-Verwey-Overbeek (DLVO)–like potential, i.e., an interaction potential with a primary and a secondary minimum, capturing the main physical features of the magnetocapillary interaction, which is relevant for self-assembly. [less ▲]

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See detailHow does an ice block assembly melt?
Dorbolo, Stéphane ULg; Ludewig, François ULg; Vandewalle, Nicolas ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012)

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See detailHow relative humidity affects random packing experiments
Vandewalle, Nicolas ULg; Lumay, Geoffroy ULg; Ludewig, François ULg 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 ▲]

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See detailAntiphase synchronization of electrically shaken conducting beads
Mersch, Eric ULg; Vandewalle, Nicolas ULg

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 84

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See detailAn Experimental Approach to Link Powder Physical Properties to 3D Particle Shape
Califice, Arnaud ULg; Lumay, Geoffroy ULg; Vandewalle, Nicolas ULg et al

in Particulate Systems Analysis 2011 (2011, September)

A series of samples have been characterized by 3D image analysis (using X-Ray microtomography). The samples consist of blends of metallic particles: steel shot abrasives (“balls”), steel fibres and ... [more ▼]

A series of samples have been characterized by 3D image analysis (using X-Ray microtomography). The samples consist of blends of metallic particles: steel shot abrasives (“balls”), steel fibres and angular steel grit particles. The blends were systematically prepared in different proportions of the raw products. Various shape and size parameters were measured on the particles: equivalent volume diameter (dV), maximum inscribed sphere diameter (dIN), particle length (maximum Feret diameter), particle elongation (El), particle flatness (Fl) etc. The results are expressed as statistical shape and size parameters, expressed both as volume and number weighted distributions. The blends have been tested for compaction using a cylindrical container which experiences a series of 500 free falls over a height of 3mm. The compaction dynamics was monitored using a sensor that measures the evolution of the solid volume fraction as a function of the tap number. From the obtained compaction curve, the Hausner ratio and a flowability index were extracted. The same blends have also been analysed using a rotating drum at different rotation speeds to analyze the evolution of the flowing angle. As the system is based on the analysis of a time sequence of 50 images (separated by 0.5 sec) it is possible to measure the intermittent character of the powder flow. The resulting measure is a cohesive index of the powder. The results obtained from physical testing were systematically plotted as a function of various statistical indices of the shape and size distributions in order to reveal correlations between particle shape properties and physical behaviour. Some clear trends appeared, demonstrating the influence of particle shape on powder physical properties. [less ▲]

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See detailEpidemic spreading in a finite-precision BA model
Ababou, Malika ULg; Vandewalle, Nicolas ULg; MOUSSA, Najem 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 ▲]

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See detailManipulation of Droplets onto a Planar Interface
Gilet, Tristan ULg; Terwagne, Denis ULg; Vandewalle, Nicolas ULg et al

in miller, reinhard; liggieri, libero (Eds.) Progress in Colloid and Interface Science, 2 (2011)

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See detailHysteretic behavior in three-dimensional soap film rearrangements
Vandewalle, Nicolas ULg; noirhomme, matial; Schockmel, Julien ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 83

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See detailInfluence of a reduced gravity on the volume fraction of a monolayer of spherical grains
Dorbolo, Stéphane ULg; scheller, tom; Ludewig, François ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 84

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See detailImpact of liquid droplets on granular media
Delon, Giles ULg; Terwagne, Denis ULg; Dorbolo, Stéphane ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011)

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See detailPhase transitions in vibrated granular systems in microgravity
Opsomer, Eric ULg; Vandewalle, Nicolas ULg; Ludewig, François ULg

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011)

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