Physique des mouvements naturels dans les fluides

Mouvements collectifs en environnement complexe, Physique des écoulements dans les végétaux, Foule et interactions: des nageurs aux bulles, Hydrodynamique de micro-nageurs, Le plancton pour la physique

GDR : Physique des Plantes /Liquides aux Interfaces / Polymères & Océans / Microfluidique / Mephy

Séchage/cavitation des feuilles Dollet, Marmottant

Brodribb (Tasmanie), Cochard, Badel (Inrae)

Microalgues et milieux complexes Peyla, Rafaï Bertin, Coasne (LIPhy-PSM)

Foule de Micronageurs Peyla, Rafaï Faure (Maths, ENS), Maury (Maths, Orsay)

Bulles, Acoustique & Microstructures 3D

Dollet, Marmottant, Stephan Bossy (LIPhy-Optima)

Plancton luminescent & fluides complexes

Peyla, Rafaï Bodiguel, Pignon (LRP, Grenoble)

Synthèse Nageurs interfaciaux biomimétiques

Stephan Lambert (Bruxelles)

Sloshing in a Hele-Shaw cell: experiments and theory

–5 –4 –3 –2 –1 0 1 2 3 4 5cm

0

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(a) (b)

(c)1

FIGURE 1. (a) Sketch of the experimental set-up. (b) Raw image of the air/liquid interface,taken from the experiment without added glycerol and at a forcing frequency of 3.5 Hz.(c) Binarized image obtained after thresholding.

Solution Composition Kinematic viscosity Density Temperature(mm2 s�1) (g cm�3) (�C)

1 Base fluid(95 % ethanol + 5 % isopropanol)

1.7934 0.8047 21.0

2 Base fluid + 5 % glycerol 2.2783 0.8305 20.03 Base fluid + 20 % glycerol 3.7069 0.8807 20.54 Base fluid + 25 % glycerol 6.4688 0.9294 20.05 Base fluid + 30 % glycerol 11.853 0.9786 20.06 Base fluid + 40 % glycerol 15.319 0.9997 20.57 Base fluid + 45 % glycerol 21.388 1.0225 20.08 Base fluid + 55 % glycerol 40.594 1.0697 20.59 Base fluid + 62 % glycerol 63.428 1.0987 20.5

TABLE 1. Physical properties of the solutions used at the temperature of the experiments.

2. Experimental methods

The experimental set-up used to generate the sloshing waves in the narrow containerand to measure the free-surface displacement is shown in figure 1(a). A Plexiglas cellof height H = 15 cm, length `= 10 cm and width ⇣ = 0.3 cm is fixed to a single-axislinear motion actuator (Aerotech PRO 165). The container is partially filled from thetop with a column of liquid of height h0 = 10 cm, that is of the same order as thecontainer’s length, h0 ⇡ `, in order to limit viscous dissipation at the bottom of thecontainer. Indeed, the effect of a finite depth h0/` enters the eigenfrequency of thefundamental mode, which is the most sensitive to finite-depth effects, through a factorp

tanh (ph0/`), which equals the infinite-depth limit within less than 1 % for h0 = `(Ibrahim 2005). We use different solutions of 95 % ethanol plus 5 % isopropanol thatis mixed with glycerol (0 %, 5 %, 25 %, 40 %, 45 %, 55 % and 62 % in volume ofglycerol). The properties of the different solutions are measured with an Anton Paarviscosimeter (SVM 3000) and summarized in table 1.

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Amortissement du ballottement

Dollet Lorenceau (LIPhy-Modi)

Gallaire (EPFL)

Bancs de poissons & écoulement

Peyla, Quilliet Dupont (LIPhy-Optima)

Mécanique de coques molles

Quilliet Coupier, Etienne, John (LIPhy-MC2)

Composition

Benjamin DOLLET Laeticia GREDY Philippe

MARMOTTANT Philippe PEYLA

Catherine QUILLIET Salima RAFAÏ Olivier

STEPHAN

Edouardo AL ALAM

(doct.) Monica BRAVO

(Post-Doc) Guillaume AMIEUX (stag.)

Ummahan SELMAN (stag.)