Abstract
Original language  English 

Supervisors/Advisors 

Award date  10 Oct 1997 
Place of Publication  Enschede, The Netherlands 
Publisher  
Print ISBNs  9036510384 
Publication status  Published  10 Oct 1997 
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Keywords
 METIS140284
 EWI16291
 IR29650
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Numerical simulation of Nonlinear water waves using a panel method: domain decomposition and applications. / de Haas, P.C.A.
Enschede, The Netherlands : FEBO druk b.v., 1997. 191 p.Research output: Thesis › PhD Thesis  Research UT, graduation external
TY  THES
T1  Numerical simulation of Nonlinear water waves using a panel method: domain decomposition and applications
AU  de Haas, P.C.A.
PY  1997/10/10
Y1  1997/10/10
N2  In studying the influence of water waves on constructions such as dikes, wave breakers and offshore constructions, on ships but also on natural processes such as sediment transport and changes in bottom topography, more and more use is made of numerical models. An important class of such models consists of models in which the flow is described by potential theory. On the one hand the assumptions made in potential theory are valid in many studies, on the other hand the description  its field equation is Laplace's equation for the velocity potential  offers many possibilities for finding solutions with numerical models. The panel method is a numerical method which makes use of a boundary integral formulation for Laplace's equation, so that only the boundaries of the fluid domain have to be covered with grid points. Moreover this enables a natural description of the movement of the free surface in the time domain, which is determined by nonlinear dynamical and kinematical boundary conditions. Nonlinearity of the freesurface boundary conditions is often of importance in studying the influence of waves in coastal and ocean engineering. In this thesis a twodimensional and threedimensional numerical model are studied, based on a panel method, for the description of nonlinear water waves. The focus is on two important aspects: firstly the dependence of the computational effort on the number of grid points and secondly some specific numerical difficulties which arise when the method is used in applicationlike computations. With respect to the former aspect, a domain decomposition technique is studied. The latter aspect is studied for some examples and the suitability and limitations of some parts of the method for these examples are investigated. In more detail the contents of this thesis is as follows. For the domain decomposition technique, an iterative method is chosen in which the domain is divided in the horizontal direction. The lengthtoheight ratios of the subdomains, among other things, determine the convergence of the iterative method. Because the domains in problems involving water waves generally have large lengthtoheight ratios, relatively many subdomains can be chosen with a limited loss of convergence. As a consequence the panel method can be applied much more efficiently with domain decomposition. In the case of subdomains with fixed lengthtoheight ratios, the computational costs per time step depend at most linearly on the length of the domain.
AB  In studying the influence of water waves on constructions such as dikes, wave breakers and offshore constructions, on ships but also on natural processes such as sediment transport and changes in bottom topography, more and more use is made of numerical models. An important class of such models consists of models in which the flow is described by potential theory. On the one hand the assumptions made in potential theory are valid in many studies, on the other hand the description  its field equation is Laplace's equation for the velocity potential  offers many possibilities for finding solutions with numerical models. The panel method is a numerical method which makes use of a boundary integral formulation for Laplace's equation, so that only the boundaries of the fluid domain have to be covered with grid points. Moreover this enables a natural description of the movement of the free surface in the time domain, which is determined by nonlinear dynamical and kinematical boundary conditions. Nonlinearity of the freesurface boundary conditions is often of importance in studying the influence of waves in coastal and ocean engineering. In this thesis a twodimensional and threedimensional numerical model are studied, based on a panel method, for the description of nonlinear water waves. The focus is on two important aspects: firstly the dependence of the computational effort on the number of grid points and secondly some specific numerical difficulties which arise when the method is used in applicationlike computations. With respect to the former aspect, a domain decomposition technique is studied. The latter aspect is studied for some examples and the suitability and limitations of some parts of the method for these examples are investigated. In more detail the contents of this thesis is as follows. For the domain decomposition technique, an iterative method is chosen in which the domain is divided in the horizontal direction. The lengthtoheight ratios of the subdomains, among other things, determine the convergence of the iterative method. Because the domains in problems involving water waves generally have large lengthtoheight ratios, relatively many subdomains can be chosen with a limited loss of convergence. As a consequence the panel method can be applied much more efficiently with domain decomposition. In the case of subdomains with fixed lengthtoheight ratios, the computational costs per time step depend at most linearly on the length of the domain.
KW  METIS140284
KW  EWI16291
KW  IR29650
M3  PhD Thesis  Research UT, graduation external
SN  9036510384
PB  FEBO druk b.v.
CY  Enschede, The Netherlands
ER 