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Numerical simulation of two-dimensional vortex shedding for marine applications

Xu, G; (2013) Numerical simulation of two-dimensional vortex shedding for marine applications. Doctoral thesis (PhD), UCL (University College London). Green open access

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Abstract

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.

Type: Thesis (Doctoral)
Qualification: PhD
Title: Numerical simulation of two-dimensional vortex shedding for marine applications
Open access status: An open access version is available from UCL Discovery
Language: English
Keywords: numerical simulation; vortex shedding; boundary element method; Green function
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1398681
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