| Popis: |
We are interested in acoustic scattering by bubble clouds in water at frequencies and densities such that the acoustic wavelength is large relative to the average distance between bubbles and large relative to that corresponding to the bubble resonance frequency. At high frequency and moderate bubble density, bubble scattered intensity is proportional to N (the number density of the bubbles, m4), which corresponds to incoherent scattering. Effective medium theory has been shown to predict predominantly incoherent scattering at high frequencies, but coherent scattering (scattered intensity proportional to N2) at lower frequencies. An incoherent scattering assumption at low frequencies can substantially under predict the intensity of the scattered signal. Coherent (low frequency) scattering from bubble assemblages has also been explained in terms of collective shape, but this approach does not provide a means of predicting the temporal extent of the scattered signal in low frequency regimes. The literature ... |
