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Title: Finite element modelling of hydrodynamics in coastal zones
Author: Trigo Teixeira, A. A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1994
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A Finite Element Model is developed and implemented in order to study the hydrodynamics of coastal zones. The Shallow Water Equations for well mixed waters are derived integrating the Reynolds Equations along the water depth, using the surface and bottom stress laws, and taking into account the geostrophic acceleration. The system of equations is derived in conservation form. The Euler-Taylor-Galerkin scheme is used to discretize the system of equations, with the temporal discretization preceding the spatial discretization. In the process, triangular elements are used, taking advantage of exact quadrature laws and of the meshing flexibility that such elements provide. Marching in time is done explicitly and stability controlled by the smallest element present in the grid. Analytical solutions for the linearized shallow water equations are revisited and used to assess the model's performance. A rectangular and a polar basin with constant bathymetry and closed at one end are used to test the model. Two algorithms are presented for mesh generation, one generates unstructured meshes and the other structured meshes. A methodology is devised in order to blend both types of meshes to produce an unstructured-structured hybrid mesh and the final connectivity matrix from the contribution of each individual mesh. Particular emphasis is put on the bathymetry modelling process. A new methodology is developed to obtain the information from hydrographic charts converting it into digital format using a digitizer device driver, written with the specific needs of the problem at hand. A Delaunay triangular irregular network is used to encode bathymetric information. The bathymetric information is then automatically transferred, superimposing the computational grid to the triangular irregular network, solving a point-in-triangulation query and interpolating linearly from the background grid. Two case studies are presented simulating tidal flow.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available