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| Author(s): |
José Renato Alcarás
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2019-01-31 |
| Examining board members: |
Alexandre Souto Martinez;
André Luis Baggio;
Antonio Adilton Oliveira Carneiro;
Glauber José Ferreira Tomaz da Silva
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| Advisor: | Alexandre Souto Martinez |
| Abstract | |
The sound wave scattering aims to understand the propagation nature of scattered and incident sound waves, for different structures and geometries of the scattering centers that form a disordered environment. In the literature, in general, we obtain information regarding the acoustic scattering in regions distant from the scattering centers (far-field approximation), for some incident wave- forms and scattering particles. In order to understand the undulatory behavior in regions close to and within the scattering center, our study provides an analytical description of the acoustic radiation fields in these regions. First, the problem considered is the scattering of an acoustic plane wave (previously traveling through an ideal newtonian fluid) by a spherical fluid particle, with distinct acoustic characteristics from the initial fluid. Still, it is determined the internal acoustic energy stored in this scattering center, as a function of the scattering spheres volume, as well as the wavelength in its interior, its amplitude and the density of the scattering center. Later, the scattering materials are considered to be viscoelastic (which exhibit viscous and elas- tic behavior when subjected to external forces), as they are feasible in the modeling of biological cells and polymers in general. For such, we deal formally with elastic materials physics, such as deformations and tensions, in order to deal with the Kelvin-Voigt viscoelastic model used in this problem. Were determined closed formulas for the scattering coefficients for this problem (as well as the internal wave coefficients), from the solution of a linear system of equations. The results allow the construction of a fundamental theory for a generalized study of sound wave scattering by viscoelastic materials, which is a goal to be achieved in a near future. (AU) | |
| FAPESP's process: | 17/09354-0 - Acoustic wave scattering and internal fields analysis of viscoelastic materials |
| Grantee: | José Renato Alcarás |
| Support Opportunities: | Scholarships in Brazil - Master |