# Reduced residence time of droplet impact on heated surfaces

## TL;DR

This paper introduces a heat-induced bouncing-with-spray mode that significantly reduces droplet residence time on heated surfaces, with a scaling law explaining the transition between bouncing modes.

## Contribution

The study identifies a novel bouncing-with-spray mode triggered by heat, providing a simple, reliable method to reduce droplet residence time and proposing a scaling law for mode transition.

## Key findings

- Bouncing-with-spray mode reduces residence time compared to traditional retraction-bouncing.
- Vapor bubble bursts create holes in the liquid film, facilitating faster recoiling.
- A scaling law accurately predicts the transition boundary between bouncing modes.

## Abstract

The impact of droplets is a ubiquitous phenomenon, and reducing the residence time of the impact process is important for many potential applications. In this study of the impact dynamics on heated surfaces, we identify a mode of droplet bouncing (bouncing-with-spray mode) that can reduce the residence time significantly compared with the traditional retraction-bouncing mode. Comparing with other strategies to reduce the residence time, this approach induced by heat is simple and reliable. The reduction in the residence time is due to the burst of vapor bubbles in the liquid film, which results in the formation of holes in the liquid film and consequently the recoiling of the liquid film from the holes. A scaling law is proposed for the transition boundary between the retraction-bouncing mode and the bouncing-with-spray mode in the film boiling regime, and it agrees well with the experimental data. This model can also explain the transition between these two modes in the transition boiling regime.