English (United States)
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.
Natter, Joseph Ross Ungar, "Turbulence in Superfluid 4-He Films around Substrate Defects" (2017). Honors Theses - All. 1834.
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