Liquid jet rebound upon impact on a soft gel

TL;DR

This study demonstrates that liquid jets can rebound off soft gels through a stable, contact-based mechanism, independent of wetting properties or surface tension, revealing a new rebound phenomenon distinct from traditional air-layer dependent cases.

Contribution

It introduces a novel liquid jet rebound mechanism on soft gels that does not rely on air layers and is insensitive to wetting properties, expanding understanding of jet-surface interactions.

Findings

Liquid jets rebound stably on soft gels via a dimple-following mechanism.

Rebound stability is independent of wetting properties and surface tension.

The phenomenon occurs even with direct liquid-gel contact, unlike traditional rebound cases.

Abstract

A liquid jet can stably bounce off a sufficiently soft gel, by following the contour of the dimple created upon impact. This new phenomenon is insensitive to the wetting properties of the gels and was observed for different liquids over a wide range of surface tensions, $\gamma$ = 24--72 mN/m. In contrast, other jet rebound phenomena are typically sensitive to $\gamma$: jet rebounds off a hard solid (e.g. superhydrophobic surface) or another liquid are possible only for high and low $\gamma$ liquids, respectively. This is because an air layer must be stabilized between the two interfaces. For a soft gel, no air layer is necessary and jet rebound remains stable even when there is direct liquid-gel contact.