Attempts to observe acoustic wave turbulence

Abstract

High‐amplitude, low‐frequency, broadband acoustic excitation of a medium should lead to a cascade of energy that is analogous to the Kolmogorov turbulence that characterizes vortex eddies. The acoustic cascade should also lead to the phenomenon of classical second sound [Larraza and Putterman, Phys. Rev. Lett. 57, 2810 (1986)]. Attempts to observe the turbulent acoustic power spectrum e(ω) ∝ ω −3/2 and higher‐order correlations, in controlled laboratory experiments, are being carried out in the Leo P. Delsasso Acoustics Labs at UCLA. The Allen and Rudnick high‐frequency siren [J. Acoust. Soc. Am. 19, 857 (1947)] is being used as a source. In the reverberation room amplitudes of about 160 dB have been achieved. While effects of higher harmonics and scattering of sound by sound can be seen, the intensity level is still apparently about 10 dB below the threshold for acoustic turbulence. [Work supported by DOE.]High‐amplitude, low‐frequency, broadband acoustic excitation of a medium should lead to a cascade of energy that is analogous to the Kolmogorov turbulence that characterizes vortex eddies. The acoustic cascade should also lead to the phenomenon of classical second sound [Larraza and Putterman, Phys. Rev. Lett. 57, 2810 (1986)]. Attempts to observe the turbulent acoustic power spectrum e(ω) ∝ ω −3/2 and higher‐order correlations, in controlled laboratory experiments, are being carried out in the Leo P. Delsasso Acoustics Labs at UCLA. The Allen and Rudnick high‐frequency siren [J. Acoust. Soc. Am. 19, 857 (1947)] is being used as a source. In the reverberation room amplitudes of about 160 dB have been achieved. While effects of higher harmonics and scattering of sound by sound can be seen, the intensity level is still apparently about 10 dB below the threshold for acoustic turbulence. [Work supported by DOE.]