Unit:
Κατεύθυνση Φυσική των Υλικών (ΒΑΣΙΚΗ ΦΥΣΙΚΗ)Library of the School of Science
Dissertation committee:
Stefanou Nikolaos (Επιβλέπων) Professor of National and Kapodistrian University, Section of Solid State Physics
Morvan Bruno (Εξεταστική επιτροπή) Professeour des Universites LOMC, UMR CNRS 6294, Universite Le Havre Normandie
Sainidou Rebecca (Συμβουλευτική επιτροπή) Maitre des Conferences LOMC, UMR CNRS 6294, Universite Le Havre Normandie
Rembert Pascal (Συμβουλευτική επιτροπή) Maitre des Conferences LOMC, UMR CNRS 6294, Universite Le Havre Normandie
Conoir Jean - Marc (Εξεταστική επιτροπή) Directeur de Recherche CNRS, IJLRA, Sorbonne Université Paris
Groby Jean - Philippe (Εξεταστική επιτροπή) Charge de Recherche CNRS, HDR, LAUM, UMR CNRS 6613, Le Mans Universite
Poncelet Oliver (Εξεταστική επιτροπή) Chargé de Recherche CNRS, I2M, Université de Bordeaux
Vasseur Jerome (Εξεταστική επιτροπή) Professeur des Universités, IEMN
Original Title:
Analysis and Control of Elastic Waves in Phononic Stractures of Poroelastic Inclusions in a Fluid
Translated title:
Analysis and Control of Elastic Waves in Phononic Stractures of Poroelastic Inclusions in a Fluid
Summary:
In the present thesis, an extension of the layer multiple scattering computational methodology to phononic structures of fluid-saturated poroelastic spherical bodies, combining Biot's theory with multiple-scattering techniques, is developed. The method is applied to the theoretical study, beyond the long-wavelength effective-medium approximation, of the acoustic response of double-porosity liquid-saturated granular materials consisting of close-packed hard or soft porous spheres. It is shown that variations of the pore size and/or the porosity within the millimeter- and submillimeter-sized spherical grains significantly alters the transmission, reflection, and absorption spectra of finite slabs of these materials.The calculated spectra are analyzed by reference to the acoustic modes of the constituent porous spherical grains as well as to relevant dispersion diagrams of correspondingly infinite crystals, and a consistent interpretation of the underlying physics is presented.Our results provide evidence for the occurrence of novel, unprecedented modes, localized in the sphere, which arise from slow longitudinal waves that are peculiar to poroelastic media. These modes induce some remarkable features in the acoustic behavior of these double-porosity materials under study, such as broad or narrow dispersionless absorption bands and/or directional transmission gaps. The acoustic properties of phononic (sub)microstructures, in the hypersonic (GHz) regime, can be probed, in general, by Brillouin light scattering experiments. In the present thesis we undertake a rigorous full elasto-optic theoretical approach to inelastic light scattering due to phonon-induced spatio-temporal variations of the refractive index of a medium, based on Green's functions, and derive analytical expressions for the intensities of the scattered light beams by single spherical particles in vacuum, thus improving the computational efficiency and accuracy of previous calculations. The above framework provides, also, the basis for a rigorous description of the effect for phononic crystals of colloidal spherical particles.
Main subject category:
Science
Keywords:
Phononic crystals , Poroelastic Media, Multiple Scattering Theory, Transmission and Absorption of Acoustic Waves, Brillouin Inelastic Light Scattering
Number of references:
104
