Orbits and reversals of a drop rolling inside a horizontal circular hydraulic jump

TL;DR

This paper investigates the complex motion of a non-coalescing drop inside a circular hydraulic jump, revealing periodic and irregular behaviors, and models the dynamics considering the drop as a rigid sphere with observed internal rotation.

Contribution

It introduces a model for drop dynamics inside a hydraulic jump, capturing orbital motion and internal rotation, supported by experimental observations.

Findings

Drop exhibits periodic and irregular orbital motions.

Internal rotation of the drop is experimentally confirmed.

Model reproduces observed orbital behaviors.

Abstract

We explore the complex dynamics of a non-coalescing drop of moderate size inside a circular hydraulic jump of the same liquid formed on a horizontal disk. In this situation the drop is moving along the jump and one observes two different motions: a periodic one (it orbitates at constant speed) and an irregular one involving reversals of the orbital motion. Modeling the drop as a rigid sphere exchanging friction with liquid across a thin film of air, we recover the orbital motion and the internal rotation of the drop. This internal rotation is experimentally observed.