Mathieu Pellegrin has been awarded the Poster Prize (2nd rank) during the international conference Flow14 which took place at the University of Twente (Netherlands), from the 18th to the 21st of May 2014.
Abstract of the poster entitled "Cavitation propagation in a biomimetic device" (M. Pellegrin, Y. Yip, F. Celestini, Y. Bouret, M. Argentina, X. Noblin) :
Cavitation is the formation of vapor bubbles within an initially stretched and homogeneous liquid medium. This phenomenon is common either in nature (trees, ferns), in engineering (boat propellers) and in medicine (lithotripsy). A natural example of cavitation, due to quasi-static tension, is the ejection of fern spores by sporangia . This catapult mechanism is triggered by the fast appearance of nucleation bubbles in the cells composing the sporangium and placed under negative pressure. We observed, for the first time, at very high speed imaging (1.5 million fps) that nucleation events are correlated : Nucleation in neighboring cells propagates very quickly. We are interested in this dynamics with different points of view : models, numerical simulation, and experiments on bio-mimetic devices. Numerical simulations allow us to access very small spatial and temporal scales. We use molecular dynamics as simulation method in order to understand the interaction between nucleation and walls movement. For experimental study, we choose a bio-mimetic approach using microfluidics devices made in hydrogels  . This experimental study allows us to control system geometry and to put neighbor cells under a tension of -20 MPa. We observed the propagation of nucleation from cell to cell, at the speed of several hundred meters per second. We studied the propagation mechanism and compare our model to experiments.
 X. Noblin et al., The fern sporangium : a unique catapult, Science, 2012.
 T. D. Wheeler and A. D. Stroock, The transpiration of water at negative pressures in a synthetic tree, Nature, 2008
 O. Vincent et al., Birth and Growth of Cavitation Bubbles within Water under Tension Confined in a Simple Synthetic Tree, Phys. Rev. Lett. 108, 184502 (2012)
Fluides & Matériaux Complexes, Doctorants/Post-doctorants, MIMIC
Dans la même rubrique :