Dynamics of superfluid helium in low gravity

The subject of this dissertation is the development of a computational fluid dynamics (CFD) simulation that models the unique characteristics of superfluid helium. The simulation is based on the commercial CFD code FLOW-3D.; The code implements Landau's "two fluid" model of helium II, which postulates a "superfluid" component (which has zero viscosity and zero entropy) and a "normal fluid" component (which has the properties of helium I). The superfluid and normal fluid are completely interpenetrating but have individual velocity fields as well as separate sets of equations for momentum and continuity. Under certain conditions, a current of the superfluid will flow indefinitely, similar to the phenomenon of persistent electrical currents in superconducting metal rings.; The modeling of the interaction between the two fluids is controlled by experimentally-based critical velocity thresholds and the Gorter-Mellink mutual friction model in the bulk liquid. A method of coupling the two fluids at the free surface and calculating the motion of the free surface has been developed based on extrapolation of observations of reversible changes in angular momentum by experimenters in the field.; The computer model is compared to closed-form solutions and to experimental 1-g He II slosh measurements gathered as part of this research to partially verify the simulation's accuracy. Predictions of He II behavior in low-g conditions are calculated and the results of the single-fluid model are compared to the two-fluid model. The impulse response of He II in a rotating spacecraft calculated using the two-fluid model is very different from the fluid motion calculated from a single-fluid model.