Cyclones and attractive streaming generated by acoustical vortices

TL;DR

This paper demonstrates that acoustical vortices can generate controllable cyclonic and attractive streaming flows, enabling contact-less vortical flow control using radiation pressure effects.

Contribution

It introduces a novel method to induce and control axial vortical flows with acoustical vortices, expanding their application scope beyond particle manipulation.

Findings

Acoustical vortices can induce cyclonic flows.

Flow topology can be controlled by beam properties.

Attractive streaming directed toward the transducer is achievable.

Abstract

Acoustical and optical vortices have attracted large interest due to their ability in capturing and manipulating particles with the use of the radiation pressure. Here we show that acoustical vortices can also induce axial vortical flow reminiscent of cyclones whose topology can be controlled by adjusting the properties of the acoustical beam. In confined geometry, the phase singularity enables generating attractive streaming with a flow directed toward the transducer. This opens perspectives for contact-less vortical flow control.