| Wed October 4th 2017 16:00 – 17:00 ZH286 | Seminar | Playing in a liquid pool: levitating drops and tightrope-dancing bubbles Alexis Duchesne |
Details:At the surface of the liquid pool,We will discuss the case of drops in levitation (so-called Leidenfrost effect) on a heated liquid pool. Particularly we will see that a volatile liquid drop placed on the surface of a non-volatile liquid pool reaches the Leidenfrost state as soon as the liquid of the pool is just hotter than the drop boiling point, with no apparent Leidenfrost threshold. We will also discuss the flow induced by the drop in the pool. Plunging further in the liquid pool, We will see that bubbles nucleated on a horizontal hot wire immersed in a subcooled liquid pool exhibit counterintuitive behavior: the bubbles detached and then slide along the horizontal heated wire. We will first discuss some physical arguments explaining why a bubble is still attracted by the wire. Further, we will describe the different states of organization for bubbles on the wire surface: - A regime called “free” where bubbles freely circulate on the wire surface, interacting each other. We will give an explanation for this propulsion phenomenon and we will also describe the effect of this bubbles circulation on the thermal boundary layer. - A regime called “clusters” where bubbles aggregate in motionless clusters at the wire surface.  | ||
