Self-organization of ultrasound in viscous fluids

TL;DR

This paper demonstrates how ultrasonic fields in viscous fluids can spontaneously form patterns and localized states due to thermal nonlinearities and far-from-equilibrium conditions, both theoretically and experimentally.

Contribution

It provides the first combined theoretical and experimental analysis of pattern formation and bistability in acoustics within viscous fluids under external driving.

Findings

Ultrasonic pattern formation observed in viscous fluids.

Bistable regimes with localized ultrasonic states identified.

Thermal nonlinearity drives the observed effects.

Abstract

We report the theoretical and experimental demonstration of pattern formation in acoustics. The system is an acoustic resonator containing a viscous fluid. When the system is driven by an external periodic force, the ultrasonic field inside the cavity experiences different pattern-forming instabilities leading to the emergence of periodic structures. The system is also shown to possess bistable regimes, in which localized states of the ultrasonic field develop. The thermal nonlinearity in the viscous fluid, together with the far-from-equilibrium conditions, are is the responsible of the observed effects.