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Title: Mesh adaptation for pseudospectral ultrasound simulations
Author: Wise, Elliott Steven
ISNI:       0000 0004 7661 2425
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2018
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High-intensity focussed ultrasound (HIFU) is an emerging cancer therapy that holds great promise, as it is minimially invasive, requires no ionising radiation, and can treat small volumes precisely. However, currently therapies are hindered by an inadequate capacity for treatment planning, as the interactions between the sound waves and tissue are complex and difficult to simulate. The Fourier pseudospectral method is one way of efficiently performing these simulations, as it can provide high accuracies with low computational costs. However, it is typically used with uniform computational meshes, wasting resolution in regions of the simulation where only low frequencies are present, and typically under-resolving the acoustic field in the focal region. This thesis addresses this problem in two ways: First, a bandwidth-based measure of the spatial resolution requirements for a model solution is developed and integrated into a moving mesh method. This allows spatially and temporally-varying resolution requirements to be met. Bandwidth-based meshes are shown to perform very well when compared with current mesh adaptation approaches. Second, a technique is presented for discretising arbitrary acoustic source distributions that does not rely on the source's region of support coinciding with the mesh. This not only allows sources to be represented with adaptive meshes, but greatly improves the accuracy of source discretisations for uniform meshes as well. These two contributions are of vital importance in the context of HIFU simulation, and can easily be applied to the many other problems for which the Fourier pseudospectral method is used.
Supervisor: Treeby, B. ; Cox, B. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available