Accession Number : ADA115643

Title :   A Localized Finite-Element Method for Three Dimensional Ship Motion Problems,


Personal Author(s) : Bai,Kwang June

PDF Url : ADA115643

Report Date : May 1982

Pagination or Media Count : 22

Abstract : An application of the localized finite-element method to a three-dimensional time-harmonic free surface flow in a canal is presented. Boundary conditions on both the free surface and the body are linearized and imposed on their equilibrium positions. By utilizing known set of eigenfunctions, the computation domain is reduced to a very small local domain where an eight-node linear three-dimensional element is used. Proper matching is also imposed between two sets of trial functions on the truncated boundary. To be solved are the problems concerning; (1) six degree-of-freedom radiation and diffraction in three dimensions, (2) two dimensional motion corresponding to the local flow at midship cross-sectional plane, and (3) related eigenvalues. Specifically, two sets of results for two ship locations in a canal are presented. In both cases, the eigenvalues of the local cross-sectional plane are shown to play a significant role in the three-dimensional results. A remarkable similarity between existing forces and moment and the damping coefficients corresponding to the modes of their motions are also observed in the results. The accuracy of the three-dimensional results presented here is also discussed by comparing two sets of eigenvalues computed by using two different sizes of finite elements. (Author)

Descriptors :   *Ship motion, *Mathematical models, *Finite element analysis, Canals, Three dimensional, Flow, Two dimensional, Motion, Mass, Degrees of freedom, Eigenvalues, Damping, Coefficients

Subject Categories : Numerical Mathematics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE