References of "Vandewalle, Nicolas"
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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Gilet, Tristan ULg; Vandewalle, Nicolas ULg et al

Conference (2009, November 23)

A compound drop is made of a millimetric water drop encapsulated by an oil shell. They are obtained by merging one drop of each component (water and oil). Afterwards, they are laid on a high viscosity oil ... [more ▼]

A compound drop is made of a millimetric water drop encapsulated by an oil shell. They are obtained by merging one drop of each component (water and oil). Afterwards, they are laid on a high viscosity oil bath which is vertically vibrated. When the forcing acceleration is higher than a given threshold, compound drops can bounce on the surface. We show that above a second threshold some oil contained in the shell enters in the inner water droplet. In a second experiment, we drop the compound droplet on the oil bath at rest. We can determine the range of impact speed in which capillary waves developed on the surface are able to generate an oil drop (coming from the shell) in the water drop. When the bouncing trajectories of the droplets are analyzed a correlation between the emulsion threshold and the static analysis can be made. [less ▲]

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See detailMicrofluidic on a wire
Terwagne, Denis ULg; Vandewalle, Nicolas ULg; Gilet, Tristan ULg

Poster (2009, November)

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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Gilet, Tristan ULg; Vandewalle, Nicolas ULg et al

Poster (2009, September)

Compound drops are made of a millimetric water drop encapsulated by an oil shell. They are laid on a high viscosity oil bath which is vertically vibrated. When the forcing acceleration is higher than a ... [more ▼]

Compound drops are made of a millimetric water drop encapsulated by an oil shell. They are laid on a high viscosity oil bath which is vertically vibrated. When the forcing acceleration is higher than a given threshold, compound drops can bounce on the surface. We show that above an another threshold a double emulsion occurs in the drop. We measured this emulsion threshold for various size and water/oil volume ratio of the compound drop. [less ▲]

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See detailA drop of spectroscopy
Terwagne, Denis ULg; Gilet, Tristan ULg; Vandewalle, Nicolas ULg et al

Conference (2009, May)

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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Mack, Nicolas; Dorbolo, Stéphane ULg et al

Poster (2009, March)

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See detailCharacterization of tap intensity for granular compaction
Ludewig, François ULg; Dorbolo, Stéphane ULg; Vandewalle, Nicolas ULg

in Powders and Grains 2009 (2009)

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See detailcompaction dynamics of magnetized powder
Lumay, Geoffroy ULg; Dorbolo, Stéphane ULg; Vandewalle, Nicolas ULg

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2009), 80

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See detailCompletely inelastic ball
Gilet, Tristan ULg; Vandewalle, Nicolas ULg; Dorbolo, Stéphane ULg

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2009)

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See detailAntibubbles, liquid onions and bouncing droplets
Vandewalle, Nicolas ULg; Terwagne, Denis ULg; Gilet, Tristan ULg et al

in Colloids and Surfaces A : Physicochemical and Engineering Aspects (2009), 344

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See detailDigital microfluidics on a wire
Gilet, Tristan ULg; Terwagne, Denis ULg; Vandewalle, Nicolas ULg

in Applied Physics Letters (2009), 95

In this letter, we discuss the behavior of droplets on fiber networks. An on/off transition is observed when a droplet comes around an intersection between several fibers: large droplets cross the ... [more ▼]

In this letter, we discuss the behavior of droplets on fiber networks. An on/off transition is observed when a droplet comes around an intersection between several fibers: large droplets cross the junction while small droplets remain pinned. We show that fibers perform advantageously most operations of digital microfluidics, such as multiplexed biochemical microreactions: intersections are the basic component of fiber-based microfluidic devices. [less ▲]

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See detailMotion of carbon nanotubes in a rotating drum: The dynamic angle of repose and a bed behavior diagram
Pirard, Sophie ULg; Lumay, Geoffroy ULg; Vandewalle, Nicolas ULg et al

in Chemical Engineering Journal (2009), 146(1), 143-147

The granular flow behavior of carbon nanotubes produced by the CCVD method in a laboratory continuous inclined rotary reactor and of a catalyst was experimentally studied using a rotating drum. The ... [more ▼]

The granular flow behavior of carbon nanotubes produced by the CCVD method in a laboratory continuous inclined rotary reactor and of a catalyst was experimentally studied using a rotating drum. The dynamic angle of repose of the bulk solid and the standard variation of the solid bed surface were determined as a function of rotational speed of the rotating drum and for several filling percentages of the drum. Whatever the carbon nanotube production conditions, the dynamic angle of repose and the standard variation of the solid bed depended only on the filling percentage of the drum. Results were very interesting for practical application to carbon nanotube production in an industrial continuous inclined rotary reactor, because the granular flow behavior was the same during the reaction throughout the length of the reactor and depended only on the reactor filling. A bed behavior diagram based on the drum rotational speed and on the drum filling percentage was also constructed experimentally. The flow behavior of the solid during carbon nanotube production was on the boundary between the slumping and the rolling modes, leading to a good mixing of gas and solid during the reaction and to an improvement of the mass and heat transfer in the bed. (c) 2008 Elsevier B.V. All rights reserved. [less ▲]

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See detailMullite coatings on ceramic substrates: Stabilisation of Al2O3-SiO2 suspensions for spray drying of composite granules suitable for reactive plasma spraying
Schrijnemakers, Audrey ULg; Andre, Sophie; Lumay, Geoffroy ULg et al

in Journal of the European Ceramic Society (2009), 29(11), 2169-2175

The present work deals with the preparation of stable alumina + silica suspensions with high solid loading for the production of spray-dried composite powders. These composite powders are to be used for ... [more ▼]

The present work deals with the preparation of stable alumina + silica suspensions with high solid loading for the production of spray-dried composite powders. These composite powders are to be used for reactive plasma spraying whereby the formation of mullite and the coating on a ceramic substrate are achieved in a single step process. Electrostatic stabilisation of alumina and silica suspensions has been studied as a function of pH. Silica suspensions are most stable at basic pH whereas alumina suspensions are stable at acidic pH. The addition of ammonium polymethacrylate (APMA) makes it possible to stabilise alumina and prepare a stable 50 wt% alumina + silica suspension at pH 10. The optimum amounts of dispersant and binder have been determined by zeta potential, viscosity and sedimentation measurements. Spray drying of the suspension yields composite powders whose morphology, size distribution and flowability have been characterized before realizing reactive plasma spraying tests. (C) 2009 Elsevier Ltd. All fights reserved. [less ▲]

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See detailA video multitracking system for quantification of individual behavior in a large fish shoal: Advantages and limits
Delcourt, Johann ULg; Becco, Christophe ULg; Vandewalle, Nicolas ULg et al

in Behavior Research Methods (2009), 41(1), 228-235

The capability of a new multitracking system to track a large number of unmarked fish (up to 100) is evaluated. This system extrapolates a trajectory from each individual and analyzes recorded sequences ... [more ▼]

The capability of a new multitracking system to track a large number of unmarked fish (up to 100) is evaluated. This system extrapolates a trajectory from each individual and analyzes recorded sequences that are several minutes long. This system is very efficient in statistical individual tracking, where the individual’s identity is important for a short period of time in comparison with the duration of the track. Individual identification is typically greater than 99%. Identification is largely efficient (more than 99%) when the fish images do not cross the image of a neighbor fish. When the images of two fish merge (occlusion), we consider that the spot on the screen has a double identity. Consequently, there are no identification errors during occlusions, even though the measurement of the positions of each individual is imprecise. When the images of these two merged fish separate (separation), individual identification errors are more frequent, but their effect is very low in statistical individual tracking. On the other hand, in complete individual tracking, where individual fish identity is important for the entire trajectory, each identification error invalidates the results. In such cases, the experimenter must observe whether the program assigns the correct identification, and, when an error is made, must edit the results. This work is not too costly in time because it is limited to the separation events, accounting for fewer than 0.1% of individual identifications. Consequently, in both statistical and rigorous individual tracking, this system allows the experimenter to gain time by measuring the individual position automatically. It can also analyze the structural and dynamic properties of an animal group with a very large sample, with precision and sampling that are impossible to obtain with manual measures. [less ▲]

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See detailMetastable bouncing droplets
Terwagne, Denis ULg; Gilet, Tristan ULg; Vandewalle, Nicolas ULg et al

in Physics of Fluids (2009), 21

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See detailThe mayonnaise droplet
Terwagne, Denis ULg; Mack, Nicolas; Dorbolo, Stéphane ULg et al

in Chaos (2009)

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See detailHybrid wetting state on micro-waffle textures
Caps, Hervé ULg; Vandormael, Denis; Loicq, Jerôme ULg et al

in Europhysics Letters (2009), 88

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See detailControlled flow of smart powders
Lumay, Geoffroy ULg; Vandewalle, Nicolas ULg

in Physical Review E (2008), 78(6),

The flow properties of powders are mainly due to the interplay of cohesive forces and intergrain frictional forces. We have experimentally investigated a "smart granular system" for which the ... [more ▼]

The flow properties of powders are mainly due to the interplay of cohesive forces and intergrain frictional forces. We have experimentally investigated a "smart granular system" for which the interparticle cohesion can be tuned by a magnetic field B. We show that the rheological features of such a system can be controlled. Indeed, the granular flow can be controlled or even stopped by the magnetic field. Depending on the orientation of B, different dynamical regimes can be obtained like a "dry liquid state" forming conical droplets as well as a "layered soft state". Scaling lows are given for the flow rate outside a funnel as a function of B and for the stopping threshold of the flow as a function of the funnel output diameter D. From this analysis, it appears that the flowing properties are related to the dimensionality of the magnetic aggregates. [less ▲]

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