Using streamlines to visualize acoustic energy flow across boundaries

Utilisation de flux pour visualiser le passage de l’énergie acoustique à travers la frontière entre deux milieux

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Authors
  1. Chapman, D.M.F.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
For spherical waves that radiate from a point source in a homogeneous fluid and propagate across a plane boundary into a dissimilar homogeneous fluid, the acoustic field may differ significantly from the geometric acoustics approximation if either the source or receiver is near the interface (in terms of acoustic wavelengths) or if the minimum-phase path is near the critical angle. In such cases, the entire acoustic field must be considered, including inhomogeneous waves associated with diffraction (i.e. those components that vanish with increasing frequency). The energy flow from a continuous-wave monopole point source across the boundary is visualized by tracing acoustic streamlines: those curves whose tangent everywhere is the average acoustic intensity vector. It is seen that the acoustic energy flow is not always in line with the “Snell’s law” or minimum-phase path. Also, plots of acoustic energy streamlines do not display any obvious anomaly in the vicinity of the critical angle. Finally, it is shown that there exists a law of refraction of acoustic energy streamlines across density discontinuities, analogous to Snell’s law of refraction of ray paths across sound speed discontinuities. Examples include water-to-seabed transmission and water-to-air transmission.

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Keywords
acoustic, energy, streamlines, boundary, monopole, point source, density, Snell'
Report Number
DRDC-ATLANTIC-SL-2007-337 — Scientific Literature
Date of publication
01 Dec 2007
Number of Pages
9
Reprinted from
Journal of the Acoustical Society of America, vol 124, no 1, 2008, p 48-56
DSTKIM No
CA032532
CANDIS No
531712
Format(s):
Electronic Document(PDF)

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