Nonlinear Acoustics: Propagation in a Periodic Waveguide, Scattering of Sound by Sound, Propagation through a Three-Layer Fluid, and Nonlinearity Parameters of Sea Water
Abstract
Research on nonlinear acoustics has been carried out during the 12- month period ending 30 September 1991. Progress on four primary projects (A-D): (A) Airborne acoustic Bloch waves in a periodic waveguide: Both theoretical and experimental work was done on (1) effect of modifying the structure to double the periodicity length of the waveguide, (2) propagation of narrowband Bloch wave pulses, and (3) energy transport velocity and group velocity of Bloch waves. (B) Scattering of sound by sound: Propagation curves and beam patterns were measured to investigate finger radiation, which is a degenerate form of sound scattered by sound. The results confirmed some theoretical predictions but cast doubt on others. Classical crossed beam measurements were begun, but results so far are inconclusive. (C) Finite-amplitude waves in a three-layer fluid: A high precision positioning system was designed and built for experiments to be done in a water tank. Theoretical work was also started. (D) Properties of sea water and fresh water for finite-amplitude wave calculations: Pressure, temperature, and salinity dependence were obtained for the coefficient of nonlinearity beta and a related quantity. Miscellaneous projects included ellipsoidal focusing of sound in air.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 19, 1991
- Accession Number
- ADA241294
Entities
People
- David T. Blackstock
Organizations
- University of Texas at Austin