Dissertation for the degree of Doctor of Technology to be presented with due permission for public examination and debate in Auditorium F1 at Helsinki University of Technology (Espoo, Finland) on the 27th of April, 2000, at 12 o'clock noon.

An efficient and highly accurate, Symmetric Galerkin Boundary Element Method Finite Element Method based alternating method, for the analysis of three-dimensional non-planar cracks, and their growth, in structural components of complicated geometries, is proposed. The crack is modeled by the symmetric Galerkin boundary element method, as a distribution of displacement discontinuities, as if in ...

This paper presents a comparison of numerical methods used to model large scale acoustic coupled fluidstructure interaction (FSI) problems for single and double-walled cylindrical shells. The finite element method (FEM) is used to model the structure while the fast multipole boundary element method (FMBEM) is used to model the fluid domain and both models are coupled on the shared boundary surf...

In this paper, a modification on the fixed grid finite element method is presented and used in the solution of 2D linear elastic problems. This method uses non-boundary-fitted meshes for the numerical solution of partial differential equations. Special techniques are required to apply boundary conditions on the intersection of domain boundaries and non-boundary-fitted elements. Hence, a new met...

The finite element method (FEM) is a domain technique of solving the underlying governing equation in the region. The solution obtained in the total region is ideal to study energy/defect interactions, but the extensive discretization demands vast computer resources. On the other hand, the potential savings in computation resources, due to a limited surface or boundary discretization, is the pr...

We reformulate the Johnson–Nedelec approach for the exterior two-dimensional Stokes problem taking advantage of the parameterization of the artificial boundary. The main aim of this paper is the presentation and analysis of a fully discrete numerical method for this problem. This one responds to the needs of having efficient approximate quadratures for the weakly singular boundary integrals. We...

The three-dimensional electrostatic field configuration in gas ionization detectors has been simulated using an efficient and precise nearly exact boundary element method (NEBEM) solver set up to solve an integral equation of the first kind. This recently proposed formulation of BEM and the resulting solver use exact analytic integral of Green function to compute the electrostatic potential for...

The forward scattering from an arbitrarily shaped cylinder is characterized by its induced field ratio (IFR). This paper describes how a focused beam system is used to determine the scattering characteristics of an arbitrary-shaped cylinder. The fields of the transmitting and receiving antennas, as well as the scattered field from the cylinder, are described by equivalent fundamental Gaussian b...

this paper describes a contra-rotating propeller (crp) system to calculate the hydrodynamic characteristics and then design the optimum operational condition to be installed on two different large bulk carriers and vlcc. the method is based on boundary element method (bem) to obtain the hydrodynamic performance of any complicated configuration such as crp system, and then the optimum propeller ...