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The elastic Leidenfrost effect:  coupling vapor release and elastic deformations to power sustained bouncing

August 16 / 2:30 pm - 3:00 pm

Dr. Scott Waitukaitis
University of Leiden,
Netherlands

 

The Leidenfrost effect occurs when an object near a hot surface vaporizes rapidly enough to lift itself up and hover. Although well-understood for liquids and stiff sublimable solids, little is known about the interaction of vaporizable soft solids with superheated surfaces.  In this talk, I will introduce a new phenomenon that occurs with vaporizable soft solids: the elastic Leidenfrost effect. By dropping vaporizable hydrogel spheres onto hot surfaces I will show that, rather than hovering, they energetically bounce several times their diameter for minutes at a time. With high-speed video during a single impact, one sees high-frequency microscopic gap dynamics at the sphere-substrate interface.  Solving for the dynamics of a simplified system with a simple numerical model, I will reveal how these otherwise-hidden agitations constitute work cycles that harvest mechanical energy from the vapor and sustain the bouncing.  Quite literally, the hydrogel sphere behaves like a soft engine, where nearly all of the components are embedded into a single object made from a single material.  These findings suggest a novel strategy for injecting mechanical energy into soft materials, with potential relevance in fields ranging from soft robotics to active matter.

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Detalles

Fecha:
August 16
Hora:
2:30 pm - 3:00 pm

Lugar

Sala Seminarios 3er piso, DFI
Av Blanco Encalada 2008
Santiago, Chile
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