Tractor beam on the water surface

TL;DR

This paper introduces a novel method for remotely manipulating objects on water surfaces using nonlinear waves generated by a vertical plunger, enabling control over floaters at a distance through engineered surface flows.

Contribution

It presents a new approach to remote object manipulation on water surfaces by creating complex flow patterns with nonlinear waves, expanding beyond traditional Stokes drift models.

Findings

Successful remote manipulation of floaters using surface waves.

Engineered flow patterns include inward/outward jets and vortices.

Method works for both gravity and capillary waves.

Abstract

Can one send a wave to bring an object from a distance? The general idea is inspired by the recent success in moving micro particles using light and the development of a tractor beam concept. For fluid surfaces, however, the only known paradigm is the Stokes drift model, where linear planar waves push particles in the direction of the wave propagation. Here we show how to fetch a macroscopic floater from a large distance by sending a surface wave towards it. We develop a new method of remote manipulation of floaters by forming inward and outward surface jets, stationary vortices, and other complex surface flows using nonlinear waves generated by a vertically oscillating plunger. The flows can be engineered by changing the geometry and the power of a wave maker, and the flow dissipation. The new method is robust and works both for long gravity and for short capillary waves. We use a novel method of visualising 3D particle trajectories on the surface. This letter introduces a new conceptual framework for understanding wave-driven flows. The results form the basis for remote manipulation of objects on the fluid surfaces and will help better understanding motion of floaters on the ocean surface and the generation of wave-driven jets.