Dynamical stabilization and vibro-equilibrium
Kapitza's pendulum experiment consists in stabilizing a pendulum in its upside down position using a fast oscillating external forcing. Interestingly, high vibrations
can also be used to stabilize fluids in unexpected positions. For vertical shaking, we have shown that liquid layers could be stabilized above an air layer,
and that it is possible to float under such levitating layer ! When the shaking is performed along an arbitrary direction,
new equilibrium positions can appear leading to stabilized liquid walls on which it is possible to surf !
Shaping a liquid with vibrations
The shape of a large liquid interface under standard experimental condition is horizontal due to gravity. However, one can use vibrations to modify the interface's shape resulting in so-called vibro-equilibrium. In this video, we show the interface of viscous silicon oil submitted to high frequency (100 Hz) vibration. Thanks to the vibrations, we were able to trap air bubbles under the liquid at precise locations shaped as a smiley. The presence of the air bubble 'pushes' the liquid, which results in printing the smiley shape of bubbles at the liquid surface.
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