Testing the accuracy of a three-dimensional acoustic coupled mode model
Ehret, Laura L.
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The three-dimensional coupled mode sound propagation model of Chiu and Ehret (1990) is tested for its accuracy in modeling horizontal sound refraction. The test is achieved by comparing results generated by this model with exact analytic solutions to a parabolic approximation of the Helmholz Equation (Seigman, et al., 1990). Specifically, the acoustic wavefields associated with two cases of horizontally variable sound speed are considered. In Case I the sound speed varies only with azimuth, while in Case II there is radial and azimuth variation. The acoustic quantities used for the comparison included the modal modulation envelopes and transmission loss. Errors in the mode amplitude and phase are quantified and the significance of horizontal refraction is discussed.
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