Fast directional transport of Leidenfrost droplets on spiked surfaces

TL;DR

This paper demonstrates a novel method for rapidly transporting Leidenfrost droplets on spiked surfaces, achieving speeds up to 8.36 m/sec through a self-propulsion mechanism involving violent boiling and asymmetric spike design.

Contribution

It introduces a new approach using spiked surfaces and violent boiling to achieve unprecedented droplet transport speeds in Leidenfrost effect applications.

Findings

Maximum droplet speed of 8.36 m/sec over 10 cm

Unidirectional droplet movement due to asymmetric spikes

Violent boiling causes droplet bursting and rapid propulsion

Abstract

The Leidenfrost effect enables droplets to levitate above a solid surface, significantly reducing the resistance to droplet motion. In this study, a spiked surface is utilized to achieve fast directional transport of Leidenfrost droplets, with a maximum average speed reaching 8.36 m per second over a 10 cm distance,far exceeding the previously reported maximum speeds for droplet transport. When a droplet falls onto a substrate heated above the Leidenfrost temperature, it becomes trapped between spikes and levitates. The sides and bottom surface of the droplet undergo vaporization, creating a gas film between the solid wall and the droplet. However, this gas film is unstable and prone to rupture at certain points, causing the droplet to come into contact with the solid surface. Therefore, the droplets undergo violent boiling, leading to intense compression and bursting into smaller daughter droplets, which are then propelled rapidly along the substrate. Additionally, the asymmetric geometry of the spikes ensures that droplets move unidirectionally along the longitudinal direction. This study proposes a novel droplet self-propulsion mechanism, pioneering new strategies for enhancing droplet transport speed..