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Title: The role of helicity in turbulent fluid dynamics
Author: Lipscombe, Trevor
ISNI:       0000 0001 3610 8724
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 1986
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In this thesis we consider turbulent fluid systems. We develop a closure scheme in which the mean velocity field of an incompressible fluid is driven by a turbulent velocity field possessing a non-zero mean helicity. We use this to investigate the formation of large scale vortices and the behaviour of the mean kinetic energy, enstrophy and helicity. The same technique is then applied to the equations of magneto-hydrodynamics, in order to explain the self-generation of mean magnetic fields, and the joint formation of current and vortex structures. We then discuss the convection of a passive scalar by the fluid and determine an equation for the mean temperature. Finally we present a theory to account for the behaviour of a two-dimensional electrically conducting fluid subject to a constant external magnetic field driven by external forces. We explain the peaks in the power spectrum, the saturation of the magnetic and kinetic energies, and the insensitiveness of their equilibrium value on the external field. All of these are observed in numerical experiments.
Supervisor: Haar, D. ter Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Fluid dynamics ; Particles (Nuclear physics) ; Helicity ; Turbulence