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Title: Diamagnetic levitation of liquid-grain systems and liquid drops
Author: Liao , Liang
ISNI:       0000 0004 6351 3436
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2016
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This thesis describes the use of diamagnetic levitation for experimental studies of fluid and granular dynamics in a pseudo-weightless environment. A super­conducting solenoid magnet was used to generate a large 18 T inhomogeneous magnetic field in order to levitate liquid water, organic liquids and bismuth particles diamagnetically, and glass particles using the magneto-Archimedes effect. We first present an experimental study of the behaviour of a pair of magnet­ically suspended spheres in an oscillating liquid. The spheres have a density greater than that of the liquid in which they are immersed, so that vibration of the liquid results in relative motion of the spheres through the liquid, gen­erating streaming flows. Under vibration, the spheres attract one another. Spontaneous orbiting of the spheres was observed above a critical vibration amplitude. Experimental and numerical studies of the flow reveal the origin of the fluid dynamical instability. The collapse of experimental and numerical data onto a single curve shows that the fluid dynamical instability occurs at a critical value of the streaming Reynolds number. In addition we compared our experimental measurements of the relative amplitude of spheres through the vibrated liquid with existing numerical models. This thesis also describes an experimental study of the equilibrium shapes and stability of a freely levitated, spinning and electrically-charged liquid droplet. Beginning with a spherical droplet at rest, we observed the equatorial diameter of the droplet expand with increasing angular momentum, until it evolved into a triaxial shape at the theoretically predicted angular momentum. With increasing angular momentum, the droplet fissioned into two droplets of equal volume. With increasing charge, the critical angular momentum to reach the two-lobed bifurcation point and to fission the droplet was lowered. Our experimental data confirms the theoretically predicted critical charge density (Rayleigh limit) required to fission a non-rotating droplet. In addition, our experiments show that fission becomes asymmetric above a critical charge density.
Supervisor: Hill, Richard ; Swift, Michael Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available