Matched Asymptotic Expansions Solution for Low-Frequency Sound Radiation fromFluid-Loaded, Baffled Plates: Two-Dimensional Case

摘要

The method of matched asymptotic expansions is used to investigate sound radiation from fluid-loaded, baffled, thin elastic plates of dimensions small compared to the acoustic wavelength, i.e. for k(sub 0)a < < 1, where k(sub 0) is the acoustic wavenumber and a is a typical size of the plate. In this low-frequency region both nearfield quantities (plate response and surface pressure) as well as farfield radiation properties are obtained. For the two-dimensional case logarithmic gauge functions are introduced into the asymptotic expansions and a restricted matching rule is applied. At low frequencies, the plate radiates sound like a monopole, the strength of it being proportional to the net volume velocity of the plate. By using a structural reciprocity relation it is shown that the method is consistent with respect to power balance up to leading orders. Finally, the validity of the results is demonstrated by comparison with exact results. (Copyright (c) 1991 by Faculty of Technical Mathematics and Informatics, Delft, The Netherlands.)