• Login
• Admin

Clement, Bobby (2023) TWO-PHASE FLUID INTERFACIAL INSTABILITIES INDUCED BY AXISYMMETRIC ROTATION UNDER THE INFLUENCE OF AN EXTERNALLY APPLIED MAGNETIC FIELD MAGNETIC FIELD. PhD thesis, University of Nottingham.

Preview

PDF (Corrections submission) (Thesis - as examined) - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader Available under Licence Creative Commons Attribution. Download (12MB) | Preview

Abstract

In this thesis, we discuss the use of a superconducting solenoid magnet to investigate radial interfacial instabilities between two rotating immiscible, incompressible fluids of differing density. The magnetic field produced by the solenoid magnet is used to induce a radial body force on diamagnetic and paramagnetic fluids, providing an effective acceleration in the radial direction that affect the instability growth rate at the interface. The applied rotation is then controlled to induce instability for various wavenumbers, analogous with horizontal gravitational instability. The investigation is focused on a circular Hele-Shaw cell containing two fluids of non-equal density that occupy a small gap between two solid flat plates.

An experimental study is carried out by varying the angular velocity on the two-fluid system at a vertical equilibrium point in the magnetic field. The magnetic force creates an initial condition in which the more dense fluid occupies an inner circular region of a rotating circular cell, centred on the axis, while the less dense fluid occupies the outer region. Under rotation, both fluid layers experience a centripetal acceleration directed towards the axis, causing Rayleigh-Taylor instability to develop.

We were able to extract and analyse the interface between the fluid layers to determine the growth rates for increasing wavenumbers and determine the fastest growth rate. We then derived a linear growth model by approximating a highly viscous three-dimensional Stokes flow to a two-dimensional potential flow problem by taking a depth-averaged velocity over the vertical distance of our experimental cell. The model also allowed us to determine a critical angular velocity for which instability occurs. Comparisons of the fastest growing wavenumber between the model and our experimental results showed a qualitative agreement between the two. The dynamic viscosity of the fluid layers in our experiments caused a quantitative difference in our results, leading us to investigate different viscosity values. By setting the viscosity as an unknown parameter and employing non-linear curve fitting, the viscosity of both fluids layers were found to be greater than anticipated. However, we were able to show experimentally that the excitation of wavenumbers can be influenced by the angular velocity of the system.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Scase, Matthew M. Hill, Richard J.
Keywords:	Fluid Dynamics, Hele-Shaw Cell, Instability, Rayleigh-Taylor Instability, Interface, Radial Instability, Lubrication Approximation, Stokes Flow, Darcy Law, Superconductor, Magnetism, Experimental Fluid Mechanics
Subjects:	Q Science > QA Mathematics > QA801 Analytic mechanics Q Science > QC Physics > QC501 Electricity and magnetism
Faculties/Schools:	UK Campuses > Faculty of Science > School of Mathematical Sciences
Item ID:	71911
Depositing User:	Clement, Bobby
Date Deposited:	02 Jun 2025 10:01
Last Modified:	02 Jun 2025 10:01
URI:	https://eprints.nottingham.ac.uk/id/eprint/71911

Actions (Archive Staff Only)

Edit View