Research in Nonlinear Acoustics
Final rept. 1 Apr 1975-31 Aug 1984
TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
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Research in nonlinear acoustics was carried out during the period 1 April 1975 - 31 August 1986. The general goal was to understand the behavior of sound waves of finite amplitude. Progress toward this goal was made by attacking specific problems in the following areas 1 Theoretical work on periodic waves, including Burgers equation and sound beams, 2 Tones, noise, and interaction--mainly experimental, including outdoor propagation of tones and noise, suppression of sound by sound, interaction of noise with a tone, and noncollinear interaction of two tones in a rectangular waveguide 3 N waves and other transients, including development of a schlieren system, diffraction by a slit, propagation in a cylindrical tube, shock rise time, and propagation of a weak shock having a tail of arbitrary waveform 4 Propagation in inhomgenous fluids, including values of BA for sea water and nonlinear geometrical acoustics with applications to long range underwater propagation 5 Nonlinear effects in air-filled porous materials 6 Parametric receiving array 7 Focused beam parametric transmitter and 8 Miscellaneous topics. Work was also done on selected topics in linear acoustics, such as thermoacoustics and water-to-air sound transmission.