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Title: Numerical simulation of two-dimensional vortex shedding for marine applications
Author: Xu, G.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2013
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The velocity potential theory has been adopted to investigate the two-dimensional vortex shedding problems in marine hydrodynamics. The theory can find its applications to the lifting body problems such as a hydrofoil advancing near the free surface, the flow passing through an orifice of a damaged compartment, the vortex shedding at sharp edges of a marine structure. Since the viscosity of the fluid is assumed to be confined within a thin boundary layer along the surface of the structure, the fluid flow can be described by velocity potential theory. Literature review on vortex shedding has been presented. The development of relevant theories and their applications have been discussed. The challenges and suitable methodologies are investigated. When the steady motion and small amplitude unsteady motion of a hydrofoil advancing near free surface is considered, a flat vortex sheet is introduced and imposed behind the trailing edge; linear free surface conditions are imposed to study the free surface effects. Free surface Green functions, which satisfy free surface boundary conditions, are adopted to account for the free surface effects which are found to be highly significant. To study the non-linear effects of body surface boundary condition and vortex wake when the attack angle or the motion amplitude becomes moderately large, we introduce a time stepping scheme. The vortices shed from the trailing edge are approximated by introducing point vortex. The non-linear effects of body surface condition and vortex wake are investigated. Further studies on the submerged foil and surface piercing structures with vortex shedding are presented; efforts are made to investigate the non-linear wave-body interaction problems with vortex shedding. The non-linear free surface and non-linear vortex wake are found to have significant effects on the fluid flow and the hydrodynamic force.
Supervisor: Wu, G. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available