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| Author(s): |
José Renato Alcarás
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2023-02-17 |
| Examining board members: |
Alexandre Souto Martinez;
Antonio Adilton Oliveira Carneiro;
Glauber José Ferreira Tomaz da Silva
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| Advisor: | Alexandre Souto Martinez |
| Abstract | |
Continuous media properties are of great interest to science and engineering as they allow the development of materials with optimal properties to perfom certain applications. In this sense, metamaterials are those that, on a microscopic scale, have geometries and configurations that are not spontaneously found in nature, however, on a macroscopic scale, present themselves as continuous materials with unconventional properties, such as negative refractive indices and absorption coefficients anomalies. For acoustic properties, material investigations can be conducted in many different ways. Among them, the use of scattering theory stands out as a methodology to deal with the interaction of the acoustic wave with the materials. Seeking to understand this type of interaction, as well as making use of literature parameters not yet applied in the characterization of acoustic materials, this thesis proposes to investigate the acoustic fields inside fluid and viscoelastic scattering centers, and to deal with applicable scenarios for the metamaterial engineering. It is a basis study, mostly analytical, which is based on the proposal to provide a working framework for applicable developments with different fluids and viscoelastic materials. In the investigations, resonance regimes were observed between the incident waves and the scattering objects for spherical and cylindrical geometries of fluid media, which are characterized by the trapping of integer numbers of wavelengths inside the object. Examples of single scattering in scenarios involving fluids and viscoelastic materials were considered, especially those treated by the Kelvin-Voigt model, and the main differences between these media were compared with regard to the propagation of acoustic waves. Mainly, the time averages of acoustic energy and acoustic spin density deposited during the interaction of incident plane waves on these materials were defined and investigated. It is concluded from this study that the internal quantities to the scattering center considered can be useful in the development of materials and metamaterials, and it is expected that, as a perspective for the continuation of the study, the analyzes discussed here can be investigated experimentally and even further in depth from a numerical perspective. (AU) | |
| FAPESP's process: | 18/21694-4 - Acoustic metamaterials: internal fields and scattering theory |
| Grantee: | José Renato Alcarás |
| Support Opportunities: | Scholarships in Brazil - Doctorate |