Accession Number : ADA189270

Title :   Mathematical Models of Sound Waves in Fluids.

Descriptive Note : Final technical rept.,

Corporate Author : HARVARD UNIV CAMBRIDGE MA

Personal Author(s) : Birkhoff, Garrett

PDF Url : ADA189270

Report Date : 12 Aug 1987

Pagination or Media Count : 9

Abstract : The research dealt with mathematical problems of numerical ocean acoustics. These concerned the propagation of sound waves in (generally inhomogeneous) elastic fluids, with special reference ot the consistency of the elastic fluid model with 'ray theory' (Fermat-Huygens), in predicting reflection, refraction, and diffraction. The standard modern explanation in terms of relaxation times, although sixty years old, has not yet been substantiated (especially in liquids) by clear answers to many basic questions. These include the following: To what extent is the absorption of sound per wave length, alpha lamda, in air, CO2, and other dilute gases determined by the absolute temperature, T, and the ratio f/p of the frequency to the pressure? To what extent are contributions to alpha from different causes demonstrably additive, in gases and in liquids? How well can one predict the locations, breadths, and heights of the two graphs drawn in Fig. 10-12 of Pierce? How well are these correlated experimentally, in gases and in liquids? ; and How are the bulk viscosities of liquids and gases best defined and measured?

Descriptors :   *SOUND WAVES, *UNDERWATER ACOUSTICS, ACOUSTIC ABSORPTION, DILUTION, ELASTIC PROPERTIES, FLUIDS, FREQUENCY, GASES, GRAPHS, LIQUIDS, MATHEMATICAL MODELS, MATHEMATICAL PREDICTION, NUMERICAL ANALYSIS, OCEANS, ACOUSTIC REFRACTION, RELAXATION, SOUND, TEMPERATURE, THEORY, VISCOSITY, WAVE PROPAGATION, ACOUSTIC REFLECTION

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE