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DOCUMENT 



COLLECTION 



EXECUTIVE SUMMARY 



A new model of a swimbladder-bearing fish has been developed in order to provide improved predictions of the 

 resonant frequency and acoustic cross section of such a fish. The model consists of a small spherical shell in 

 water, enclosing an air cavity which supports a surface tension. The shell is a viscous, heat-conducting Newtonian 

 fluid, with the physical properties of fish flesh. A comparison of the results obtained with the new model to 

 experimental data indicates that the new model constitutes a definite improvement over previous models. The new 

 model can predict the high values of damping and elevated resonant frequencies that previous models could not. 

 The model appears to be most accurate for fish in which tension in the swimbladder wall has a minor effect on 

 resonant scattering. This includes the fish which are of interest in studies of volume reverberation and therefore, 

 the new model should be of considerable value in such studies. 



