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Home page > Séminaires > Archives séminaires > Séminaires 2013 > Séminaire MSC lundi 28 janvier 2013 à 11h30. The sound of cavitation in trees. Philippe Marmottant (LIPhy Grenoble) .

Séminaire MSC lundi 28 janvier 2013 à 11h30. The sound of cavitation in trees. Philippe Marmottant (LIPhy Grenoble)

Sauf mention contraire, les séminaires et les soutenances se déroulent à 11h30 en salle 454A du bâtiment Condorcet.


Phillipe Marmottant

The sound of cavitation in trees

The sap within trees circulates in tiny microfluidic wood vessels. Under hydric stress, in dry weather conditions, the sap can cavitate. The origin of cavitation is that water can achieve negative pressures (tension) under evaporation at the leaves.

Here, we focus on the dynamics of the cavitation bubble, which is of primary importance to understand the resistance of trees to cavitation. We use the method of artificial trees, building stiff transparent hydrogels to mimick wood channels. Our experiments on water confined in micrometric channels show an extremely fast dynamics : bubbles are nucleated within a microsecond timescale. The bubble pulsates with transient oscillations at very high frequencies in the MHz range, much higher than Minnaert’s frequency for unconfined bubbles. This rich dynamics can be accounted for by a model we developed, leading to a modified Rayleigh-Plesset equation, accounting for the confinement. These oscillations may be at the origin of the short acoustic emissions that are recorded in real trees under hydric stress. We will end up by presenting preliminary results experiments on real wood slices, combining optical and acoustical recordings.


Contact : Équipe séminaires / Seminar team - Published on / Publié le 21 décembre 2012


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