Mimicking wet colloidal suspensions with dry granular media

f(v)Athermal two-dimensional granular systems are exposed to external mechanical noise leading to Brownian-like motion. Using tunable repulsive interparticle interaction, it is shown that the same microstructure as that observed in colloidal suspensions can be quantitatively recovered at a macroscopic scale.

R.Messina, S.Aljawhari, L.Bécu, J.Schockmel, G.Lumay, N.Vandewalle, Quantitatively mimicking wet colloidal suspensions with dry granular media, Scientific Reports 5, 10348 (2015) – Open access

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The way antifoaming agents act

screenIn many industrial processes, foams are unwanted products. In order to destroy them, antifoaming agents are used… without really knowing how they act. Those antifoaming agents are dispersions of small particles, which need to break foam films efficiently. We have shown, for the first time, that buoyancy has an important part in the efficiency of those agents. In microgravity, we observed that foams added with antifoaming agent are stable for the duration of the experiment, whereas on Earth they start to disappear immediately.

http://www.nature.com/articles/npjmgrav20154

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without the hands…

Manneken Pis - Bruxelles - Belgique

We studied  the deformation of an elastic pipe submitted to gravity and to an internal fluid flow. The pipe is clamped horizontally at one end and free at the other end. As the fluid velocity increases, the shape changes from an elastic beam deflected by its own weight towards an horizontal position.

http://authors.elsevier.com/sd/article/S0889974615000651

 

 

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Cool Fluid Meeting

cfm3

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Antiresonant droplets [update]

update : paper published

GRASP | Soft Matter | University of Liège

ProlateWhen a droplet bounces onto a surface of the same liquid, coalescence occurs. This can be avoided by vibrating the liquid bath leading to a periodic bouncing. The bouncing mechanism is complex and depends strongly on the forcing parameters as shown in our previous works [1-3]. Depending on the droplet size, bouncing droplets may behave as a quantum analog, called a walker (see our Quandrop project). In a preprint that we posted on arxiv [4], we show that it is possible to select the size of droplets using droplet resonance. In this case, the droplet deformations, which are extremely sensitive to droplet size, are closely linked to the bouncing mechanism. It is also possible to “kill” one droplet size using antiresonance. The latter phenomenon corresponds to a phase shift of pi/2 between bouncing and droplet deformations. In the movie below, we show an application of our resonance/antiresonance…

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