Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549006
Title: Application of the finite-volume method to fluid-structure interaction analysis
Author: Yates, Matthew Neil
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2011
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Abstract:
This Thesis describes the numerical simulation of fluid-structure interaction (FSI) problems. A finite-volume based stress analysis code was developed and coupled to an existing in-house CFD code to form a general purpose FSI solver capable of being used with the advanced turbulence and near-wall models developed within the research group. The code has been used to study a number of physiological flows in the present work, although the general nature of the solver allows it to be used for other applications also. By using the same numerical method, implemented in a consistent manner, for both fluid and solid domains, the inefficiencies associated with using separate packages for the fluid and solid were avoided. Separate packages typically store information in different data structures; some form of software interface is required to transfer information between the two packages. This additional software layer, which is called during each FSI iteration, causes a considerable overhead. By using a single numerical mesh across both domains, the inaccuracies associated with boundary interpolation were also avoided. Typically, separate packages use meshes which do not conform at their common boundary. In order to find nodal values of the fluid pressure, say, at the solid nodes, some form of interpolation is necessary. The interpolation leads to the introduction of truncation errors. These improvements allow for more accurate and efficient FSI simulations, particularly transient cases, to be performed. The solid solver was verified against analytical solutions for a number of test cases, including: planar stress distribution in a square plate with a circular hole in the centre; axisymmetric stress in a thick walled cylinder under internal pressure, and unsteady displacement of a cantilevered beam under free vibration. Before coupled analyses were performed, the flow solver was also validated through a number of rigid walled test cases, including steady flow through a stenosed tube and unsteady flow through an aneurysm. Many physiological flows are difficult to capture due to flow separation and early transition to turbulence. The use of a low-Reynolds number k-ε turbulence model was successful at capturing the flow field over a range of physiologically relevant flow rates. Once the solid body and flow solvers had been validated in isolation, they were coupled together and applied to a number of physiological flows, namely: steady flow through an initially straight tube with a compliant wall; steady flow through a compliant stenosis, and unsteady flow through a compliant aneurysm. The results from all three test cases showed good agreement with the available experimental and numerical data in terms of wall deformation. The solid body solver also proved itself to be capable of producing high quality numerical meshes for use in other simulations. The fluid mesh was considered to be a solid body with arbitrary material properties; the required deformation was specified as prescribed displacement boundary conditions. The main benefit of this method, compared to simple elliptical grid generation methods, is that near-wall grid spacing was preserved throughout the coupled simulation.
Supervisor: Iacovides, Hector ; Craft, Timothy Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.549006  DOI: Not available
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