References of "European Physical Journal E -- Soft Matter"
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See detailMesoscale structures from magnetocapillary self-assembly
Vandewalle, Nicolas ULg; Obara, Noriko; Lumay, Geoffroy ULg

in European Physical Journal E -- Soft Matter (2013), 36

When identical soft ferromagnetic particles are suspended at some water-air interface, capillary attraction is balanced by magnetic repulsion induced by a vertical magnetic field. By adjusting the ... [more ▼]

When identical soft ferromagnetic particles are suspended at some water-air interface, capillary attraction is balanced by magnetic repulsion induced by a vertical magnetic field. By adjusting the magnetic field strength, the equilibrium interdistance between particles can be tuned. The aim of this paper is to study the ordering of particles for large assemblies. We have found an upper size limit above which the assembly collapses due to capillary effects. Before reaching this critical number of particles, defects are always present and limit the perfect ordering expected for that system. This is due to the curvature of the interface induced by the weight of the self-assembly. [less ▲]

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See detailExperimental study of a vertical column of grains submitted to a series of impulses
Lumay, Geoffroy ULg; Dorbolo, Stéphane ULg; Gerasimov, Oleg et al

in European Physical Journal E -- Soft Matter (2013), 36

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See detailEffect of a capillary meniscus on the Faraday instability threshold
Caps, Hervé ULg; NGUYN THU LAM, Khanh Dang

in European Physical Journal E -- Soft Matter (2011), 34

Threshold for Faraday instability has been experimentally measured for slightly viscous liquids. Changing the size of the container containing the fluid allows us to emphasize the role played by the ... [more ▼]

Threshold for Faraday instability has been experimentally measured for slightly viscous liquids. Changing the size of the container containing the fluid allows us to emphasize the role played by the capillary meniscus on the onset for instability. As the container is getting smaller, an upset of the critical acceleration is observed. Below a given container diameter, eigen-modes are observed along the stability curve. A dissipation terms is proposed for considering the viscous dissipation against the walls of the container. [less ▲]

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See detailBubble splitting in oscillatory flows on ground and in reduced gravity
Yoshikawa, Harunori; Zoueshtiagh, Farzam; Caps, Hervé ULg et al

in European Physical Journal E -- Soft Matter (2010), 31

The stability of centimeter scale air bubbles is studied in quiescent suspending liquid under an imposed oscillatory acceleration field. Experiments were performed in reduced- and normal-gravity ... [more ▼]

The stability of centimeter scale air bubbles is studied in quiescent suspending liquid under an imposed oscillatory acceleration field. Experiments were performed in reduced- and normal-gravity environments. A strong acceleration resulted in an instability leading to the breakups of the bubbles in both gravity environments. The breakup onset was investigated and found to be characterized by a critical acceleration acr . The influence of the liquid viscosity and the gravitational environment was studied. Empirical correlations for the onset are presented and discussed with the intention to reveal splitting mechanism. The inertial mechanism often deemed to cause the breakup of drops sub jected to a rapid gas stream is shown to give explanations consistent with the experiments. A breakup criterion for both gravitational environments is proposed through discussions from an energetic point of view. [less ▲]

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See detailDroplets sliding on fibres
Gilet, Tristan ULg; Terwagne, Denis ULg; Vandewalle, Nicolas ULg

in European Physical Journal E -- Soft Matter (2010), 31(3), 253

We present the results of a combined experimental and theoretical investigation of oil droplets sliding on fibres. First, both the axisymmetric shape and the motion of a droplet on a vertical fibre are ... [more ▼]

We present the results of a combined experimental and theoretical investigation of oil droplets sliding on fibres. First, both the axisymmetric shape and the motion of a droplet on a vertical fibre are described. The motion is shown to result from a balance between the droplet weight and the viscous stresses. On a long-term range, the droplet loses some mass through coating the fibre, which decreases its velocity. In a second time, we rationalize the behaviour of a droplet that encounters a junction between vertical and horizontal fibres. Depending on its size, the droplet may cross the junction or remain blocked. The transition is well described by an ordinary differential equation equivalent to a damped harmonic oscillator truncated to the neighbourhood of the horizontal fibre. This simple system is the basic element for more complex fiber networks that would be useful in microfluidic applications involving droplets. [less ▲]

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See detailSome aspects of electrical conduction in granular systems of various dimensions
Creyssels, Matthieu; Dorbolo, Stéphane ULg; Merlen, Alexandre et al

in European Physical Journal E -- Soft Matter (2007), 23(3), 255-264

We report on measurements of the electrical conductivity in both a 2D triangular lattice of metallic beads and in a chain of beads. The voltage/current characteristics are qualitatively similar in both ... [more ▼]

We report on measurements of the electrical conductivity in both a 2D triangular lattice of metallic beads and in a chain of beads. The voltage/current characteristics are qualitatively similar in both experiments. At low applied current, the voltage is found to increase logarithmically in good agreement with a model of widely distributed resistances in series. At high enough current, the voltage saturates due to the local welding of microcontacts between beads. The frequency dependence of the saturation voltage gives an estimate of the size of these welded microcontacts. The DC value of the saturation voltage ( similar or equal to 0.4 V per contact) gives an indirect measure of the number of welded contact carrying the current within the 2D lattice. Also, a new measurement technique provides a map of the current paths within the 2D lattice of beads. For an isotropic compression of the 2D granular medium, the current paths are localized in few discrete linear paths. This quasi-onedimensional nature of the electrical conductivity thus explains the similarity between the characteristics in the 1D and 2D systems. [less ▲]

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See detailThe influence of grain shape, friction and cohesion on granular compaction dynamics
Vandewalle, Nicolas ULg; Lumay, Geoffroy ULg; Gerasimov, O. et al

in European Physical Journal E -- Soft Matter (2007), 22(3), 241-248

This article is a review of our recent and new experimental works on granular compaction. The effects of various microscopic parameters on the compaction dynamics are addressed, in particular the ... [more ▼]

This article is a review of our recent and new experimental works on granular compaction. The effects of various microscopic parameters on the compaction dynamics are addressed, in particular the influence of the grain shape, the friction and the cohesion between the grains. Two dimensional and three dimensional systems are analysed. And the role of dimensionality will be emphasized. Theoretical and numerical investigations provide additional informations about that phenomenon. Indeed numerical models permit us to study the influence of some parameters not easily accessible experimentally. Our results show that the above mentioned parameters have a deep impact on the compaction dynamics. Anisotropic grains lead to two different compaction regimes separated by a "burst" of the packing fraction. Friction is observed to modify how the grains are arranged in the pile. This is confirmed by numerical simulations. Cohesive forces between particles inhibit compaction and lead to extremely low values of the packing fraction. [less ▲]

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See detailAir bubbles under vertical vibrations
Zoueshtiagh, F.; Caps, Hervé ULg; Legendre, M. et al

in European Physical Journal E -- Soft Matter (2006), 20(3), 317-325

This paper reports on an experimental study of the splitting instability of an air bubble a few centimetres in diameter placed in a sealed cylindrical cell filled with liquid and submitted to vertical ... [more ▼]

This paper reports on an experimental study of the splitting instability of an air bubble a few centimetres in diameter placed in a sealed cylindrical cell filled with liquid and submitted to vertical oscillations. The response of the bubble to the oscillations is observed with a high-speed video camera. It is found that the bubble dynamics is closely associated with the acceleration of the cell Gamma. For small acceleration values, the bubble undergoes minor shape deformations. With increasing acceleration values, these deformations are amplified and for sufficiently large Gamma the bubble becomes toroidal. The bubble may then become unstable and split into smaller parts. The onset of bubble division is studied and its dependency on physical parameters such as the fluid viscosity, the fluid surface tension and the initial size of the bubble is presented. It is found that the criterion for the bubble splitting process is associated with a threshold based on the acceleration of the oscillations. Above this threshold, the number of bubbles present in the cell is observed to grow until a final steady state is reached. Data analysis reveals that the final bubble size may be characterized in terms of Bond number. [less ▲]

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See detailReversing the Brazil nut effect
Ludewig, François ULg; Vandewalle, Nicolas ULg

in European Physical Journal E -- Soft Matter (2005), 18(4), 367-372

We propose a lattice model for studying the Brazil Nut Effect (BNE), i.e. the phase segregation occuring when a granular material is vertically shaked. The model considers the tap intensity and the ... [more ▼]

We propose a lattice model for studying the Brazil Nut Effect (BNE), i.e. the phase segregation occuring when a granular material is vertically shaked. The model considers the tap intensity and the mobility mu of the grains as the main physical parameters. Different mobilities for different grain species lead to segregation (BNE) patterns, reverse segregation (RBNE) patterns, "sandwhich" layered structures or vertical domains. A phase diagram (decompaction chi, mobility difference between both species Delta mu) is obtained in which the different phases are emphasized. In a narrow region of the diagram, different phases coexist. It is shown that the BNE segregation could be reversed by increasing the tap intensity or the characteristics of the grains. Numerical results are compared with earlier experimental works. [less ▲]

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See detailStability limit of a granular monolayer
Dorbolo, Stéphane ULg

in European Physical Journal E -- Soft Matter (2005), 17(1), 77-81

A granular monolayer is composed by spherical grains on a horizontal plate. The plate is then tilted until the monolayer breaks down. This critical angle has been measured for different widths and heights ... [more ▼]

A granular monolayer is composed by spherical grains on a horizontal plate. The plate is then tilted until the monolayer breaks down. This critical angle has been measured for different widths and heights of the rectangular monolayer. The highest critical angles are found when one of these two characteristic lengths is less than about 30 bead diameters. When the polydispersity is less than one percent, the monolayer may be stable till angles close to 90 degrees. Arches induce large critical angles. On the other hand, for a large and high monolayer, the critical angle saturates towards a lower value. This angle is related to the static friction of a grain on the plate. A model based on the block dynamics is proposed to describe the behavior of the avalanche angle as a function of the size of the monolayer and the polydispersity of the beads. [less ▲]

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See detailGranular size segregation in underwater sand ripples
Rousseaux, G.; Caps, Hervé ULg; Wesfreid, J. E.

in European Physical Journal E -- Soft Matter (2004), 13(2), 213-219

We report an experimental study of a binary sand bed under an oscillating water flow. The formation and evolution of ripples is observed. The appearance of a granular segregation is shown to strongly ... [more ▼]

We report an experimental study of a binary sand bed under an oscillating water flow. The formation and evolution of ripples is observed. The appearance of a granular segregation is shown to strongly depend on the sand bed preparation. The initial wavelength of the mixture is measured. In the final steady state, a segregation in volume is observed instead of a segregation at the surface as reported before. The correlation between this phenomenon and the fluid flow is emphasised. Finally, different "exotic" patterns and their geophysical implications are presented. [less ▲]

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See detailExperimental study of cracking induced by desiccation in 1-dimensional systems
Lecocq, N.; Vandewalle, Nicolas ULg

in European Physical Journal E -- Soft Matter (2002), 8(4), 445-452

We designed a simple experiment to study both the dynamical and statistical properties of cracking that occurs in a one-dimensional system composed of wet clay (or similar material) exposed to shrinkage ... [more ▼]

We designed a simple experiment to study both the dynamical and statistical properties of cracking that occurs in a one-dimensional system composed of wet clay (or similar material) exposed to shrinkage induced by desiccation. We study both the dynamical formation of cracks and the statistical characteristics of the final cracks pattern. We observe that the drying rate has a strong influence on the way cracks appear and grow. We find that the final crack width is related to the order of apparition of the cracks. We discuss the statistical distributions of cracks width and separation between two adjacent cracks. We also study the correlations between these two quantities. Our results are compared to the predictions of existing models. Finally, a comparison with another kind of clay is made. [less ▲]

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See detailGiant electrical fluctuations in metallic disordered packings
Vandewalle, Nicolas ULg; Dorbolo, Stéphane ULg

in European Physical Journal E -- Soft Matter (2001), 5(2), 129-131

We have experimentally studied granular arches through electrical measurements. The packing is composed of 2d metallic pentagons and is submitted to small taps. Large electrical fluctuations are observed ... [more ▼]

We have experimentally studied granular arches through electrical measurements. The packing is composed of 2d metallic pentagons and is submitted to small taps. Large electrical fluctuations are observed and they are distributed along power laws. The indicates the presence of long-time memory effects event the packing density remains constant around a value rho = 0.72 +/- 0.02. Large electrical fluctuations should be associated with the breaking/creation of granular arches. [less ▲]

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