Behavior of Helium II Bubble During Spin-Up and Spin-Down Motions Wrapping Around Rotating Dewar Well
Time dependent animation of spherical bubble spin-up from rest, elongate and wrap around the dewar well; and also, the fully wrapping bubble around rotating dewar well spin-down at an equilibrium rotating speed are numerically studied and simulated. Time dependent deformation of a full wrapping bubble around the rotating dewar well with and without unwrapping during the process of spin-down motion are investigated. Critical rotating speed for bubble to unwrap concerns the possibility of creating the problems of asymmetry in the imbalance liquid-vapor distribution due to sloshing dynamics perturbations in the liquid-vapor interface. Some similarity parameters are considered for how to promote the rotating well during the spin-down motion. Examples are given to illustrate the problems for dewar with various liquid-filled levels. Results show that the degree to assure the rotating bubble with and without unwrapping around the dewar well increases with increasing of the dewar rotating speed, Weber number, and also the size of the bubble.
KeywordsLiquid Helium Weber Number Time Dependent Deformation Ekman Number Helium Vapor
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