Geometry of the vapor layer under a Leidenfrost hydrogel sphere

TL;DR

This study investigates the vapor layer dynamics beneath a Leidenfrost hydrogel sphere, revealing how vaporization influences its shape and differs from traditional droplets, with implications for understanding levitation mechanisms.

Contribution

It introduces the first detailed analysis of vapor layer behavior under a hydrogel sphere, highlighting the role of vaporization in shaping the levitated object, distinct from classical Leidenfrost droplets.

Findings

Curvature inversion occurs briefly after deposition

Steady state shows no curvature inversion

Vaporization significantly influences the hydrogel's shape

Abstract

A floating Leidenfrost droplet exhibits curvature inversion of its underside, due to the balance of vapor pressure and surface tension. Using interferometric imaging, we find different behavior for a levitated hydrogel sphere. Curvature inversion is observed briefly just after deposition, but quickly gives way to a steady state with no inversion. We show the essential role of vaporization on shaping the underbelly of the hydrogel, adding a new component to the interplay between vapor pressure and elastic force