Experimental Observation of the Nonlinear Response of Single Bubbles to an Applied Acoustic Field
Abstract
An experimental technique for measuring the time-varying response of an oscillating, acoustically levitated bubble in water is developed. The bubble is levitated in a cell consisting of two concentric, cylindrical, piezoceramic transducers mounted on either end of a short glass tube. The entire apparatus forms a closed-open cylindrical tube which is driven in the cylindrical mode of (1,0,1) at a frequency f= 24kHz. Linearly polarized laser light (He-Ne 632.8, Ar-I 488.) is scattered from a bubble, and the scattered intensity is measured with a suitable photodetector positioned at some known angle from the forward, subtending some solid acceptance angle. The output photodetector current, which is linearly proportional to the light intensity, is converted into a voltage, digitized, and then stored on a computer for analysis. The scattered intensity I sub exp (t) thus obtained contains, in principle, all of the dynamical information about the oscillating bubble, and various methods of analysis are employed to examine the behavior. Complex I exp (t) behavior is also measured, with subharmonics and broad-band noise apparent in the Fourier spectra. This behavior is shown to exhibit high (greater than 2) correlation dimension, indicating the presence of more than one degree of freedom in the motion. Possible explanations for this phenomenon are discussed, including shape oscillations and chaos. Keywords: Inverse transfer functions; Physical acoustics; Lasers; Nonlinear dynamics; Optoacoustics; Chaos; Mie scattering.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1988
- Accession Number
- ADA205191
Entities
People
- Lawrence A. Crum
- R. G. Hold
Organizations
- University of Mississippi