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Water snail and microdroplets : slow and small

Sungyon Lee

Lundi 6 décembre 2010

à 15h en salle C. Brot

he first part of the talk focuses on the locomotion of a specific organism, namely, a water snail, that exhibits a striking ability to "crawl" beneath the free surface. By modeling the foot of the snail as undergoing a simple sinusoidal motion, we apply lubrication approximations for small deformations to rationalize this peculiar mode of transport and its dependency on surface tension.

While the first part is a theoretical investigation of low Reynolds locomotion, the second part of the talk features an experimental study of the flow field inside a water drop held stationary in a flowing external oil. The droplet is anchored in place by introducing a local variation in the channel height which reduces the free surface energy. Two contrasting flow regions are visible inside the drop : a fast recirculation flow is observed near the droplet boundary, while a slower flow takes place in the central region. In particular, the flow near the droplet edge displays strong three-dimensional recirculation, which requires further investigation.

ps : invitée par X. Noblin