Bistable and dynamic states of parametrically excited ultrasound in a fluid-filled cavity

TL;DR

This paper investigates the nonlinear behavior of ultrasound in a fluid-filled cavity, revealing bistable states and dynamic phenomena through a theoretical model and experimental validation.

Contribution

It introduces a simple model accounting for second harmonic effects and experimentally confirms the existence of bistable and self-modulating states in parametric ultrasound.

Findings

Bistable states of the fundamental field were observed.

Experimental results matched theoretical predictions.

Self-modulation phenomena were identified at higher driving levels.

Abstract

In this paper we have considered the problem of parametric sound generation in an acoustic resonator flled with a fluid, taking explicitely into account the influence of the nonlinearly generated second harmonic. A simple model is presented, and its stationary solutions obtained. The main feature of these solutions is the appearance of bistable states of the fundamental field resulting from the coupling to the second harmonic. An experimental setup was designed to check the predictions of the theory. The results are consistent with the predicted values for the mode amplitudes and parametric thresholds. At higher driving values a self-modulation of the amplitudes is observed. We identify this phenomenon with a secondary instability previously reported in the frame of the theoretical model.