FINITE-AMPLITUDE TRAVELING WAVES WITH BOUNDARY DISSIPATION.
HARVARD UNIV CAMBRIDGE MASS ACOUSTICS RESEARCH LAB
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Measurements have been made of the harmonic distortion of progressive waves that have initial peak pressures from 0.001 to 0.1 atmospheres at a fundamental frequency of 445 cs. These signals were propagated in air contained by a tube of diameter 1.587 cm, 2.66 cm, or 5.26 cm. Each tube was terminated with a matched load after seven wavelengths or before the experimental shock-formation distance, whichever came first. Up to thirty harmonics, whose amplitudes were within 60 dB of the initial pressure, were measured near the shock-formation distance. The measurements of the first four harmonics are compared with a correct-through-fourth-order perturbation solution of the compressible, Navier -Stokes equations. Since boundary dissipation is much more important than mainstream dissipation of the experimental circumstances of interest, only boundary dissipation is included in this solution. The theory is confirmed in all essential details. Author