Vitor Ferreira Grizzi, Ph.D. Candidate
Dr. YZ, Director of Research
November 15, 2024 | 10:30am - 12:30pm CST
This final examination will be held in 101A Talbot Laboratory.
Zoom Meeting ID: 311 065 8508 | Password: 064592
Understanding the Impact of Structure on Viscosity in Complex Liquids Using Atomic-Level Shear Stress
ABSTRACT: Understanding the role of medium-range structural ordering in liquids, particularly molten salts, is critical for grasping how atomic arrangements influence transport properties like viscosity. Medium-range ordering, characterized by spatial correlations within 5-20 Angstroms, often manifests as a pre-peak in the structure factor and indicates an arrangement of atoms beyond immediate neighbors. Despite the known impacts of the structure on properties such as viscosity, the specific mechanisms and connections to such ordering have remained unclear, especially in complex fluids like molten salts. Leveraging the Green-Kubo relations, which is an important application of the fundamental Fluctuation-Dissipation theorem, this study aims to elucidate the underlying principles connecting structure and viscosity. Investigations focused on decomposing the Green-Kubo relation for viscosity in terms of individual atomic stresses and examining how enhanced stress correlations within clusters compare to those in the bulk liquid. This idea was tested through Molecular Dynamics simulations, and its confirmation could pioneer a novel understanding of viscosity's relationship to atomic structure. Beyond theoretical implications, these insights could impact engineering applications such as Molten Salt Reactors, where clusters are observed when nuclear fuel is mixed into pure salt. Accurate computer simulations of these systems depend on precise viscosity parameters, which can be significantly affected by the evolving structure of the molten salt over time.