Turbulence in Superfluid 4-He Films around Substrate Defects

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This thesis seeks to help explain dissipation observed in third sound Superfluid 4-He by the Quantum Fluids Group at Wesleyan. Turbulence is a common hypothesis for these types of dissipation; however, it is not well understood how vortices form and nucleate in Superfluid. This project examines possible vortex formation conditions around surface defects: obstructions and bumps. We have solved for the flow fields of vortex pairs around defects, found the energy costs to vortex pair nucleation around these defects, and shown that energy cost for pair nucleation is lower for larger defects in higher velocities. Along with microscopic measurements of superfluid resonator surface defects, this model should be able to confirm whether or not observed dissipation is resulting from vortex pair formation around surface defects.

    Item Description
    Name(s)
    Thesis advisor: Ellis, Fred
    Date
    April 15, 2017
    Extent
    65 pages
    Language
    eng
    Genre
    Physical Form
    electronic
    Discipline
    Rights and Use
    In Copyright – Non-Commercial Use Permitted
    Digital Collection