Dissertation Defense Schedule
Academic Excellence
Sharing original dissertation research is a principle to which the University of Delaware is deeply committed. It is the single most important assignment our graduate students undertake and upon completion is met with great pride.
We invite you to celebrate this milestone by attending their dissertation defense. Please review the upcoming dissertation defense schedule below and join us!
PROGRAM | Mechanical Engineering
UNDERSTANDING PHONON SCATTERING AND VIBRATIONAL LOCALIZATION IN NANOPARTICLE IN ALLOY COMPOSITES
By: Ongira Chowdhury Chair: Joseph Feser
ABSTRACT
Abstract:
Embedding nanostructures in semiconductors is known to enhance phonon scattering and reduce thermal conductivity. While there are well developed processes to model these effects at low volume fractions in the independent scattering approximation, knowledge of how to most efficiently engineer these interactions in dense random nanostructures is lacking. For example, random interference patterns in highly disordered materials may lead to Anderson localized vibrational modes, which offer the promise of zero heat transfer. This dissertation explores scattering and localization phenomena in dense nanostructures through application and extension of the Frequency Domain Perfectly Matched Layer (FDPML) computational approach as well as modal analysis.
By implementing the Landauer approach via FDPML, phonon transport is investigated in dense randomly embedded nanoparticle systems. Analysis reveals that in the Mie scattering regime, the independent scattering approximation remains valid at high volume fractions up to 30%. Localization lengths are also examined both by the Landauer approach and modal analysis. Confinement is identified as primarily due to energetic confinement rather than previously hypothesized Anderson localization. This suggests that purposeful engineering of energetic confinement is a means to reduced thermal transport.
A multimode extension to FDPML method is developed, with the aim to enhance efficiency when computing transport properties. For the first time, we identify the mathematical connection between the transmission function, commonly reported for atomistic Green’s function approaches, and transmission coefficient from multimode FDPML, allowing the techniques to be compared. The technique is applied to study localization in dense nanoparticle composites.
The Process
Step-by-Step
Visit our “Step-by-Step Graduation Guide” to take you through the graduation process.From formatting your Dissertation to Doctoral Hooding procedures.
Dissertation Manual
Wondering how to set up the format for your paper. Refer to the “UD Thesis/Dissertation Manual” for formatting requirements and more.
Defense Submission Form
This form must be completed two weeks in advance of a dissertation defense to meet the University of Delaware Graduate and Professional Education’s requirements.
