Jorge D’Elía

A panel-Fourier method for free-surface flows

A panel-Fourier method for ship-wave flow problems is considered here. It is based on a three-dimensional potential flow model with a linearized free surface condition, and it is implemented by means of a low order panel method coupled to a Fourier-series. The wave-resistance is computed by pressure integration over the static wet hull and the wave-pattern is obtained by a post-processing procedure. The strategy avoids the use of numerical viscosity, in contrast with the Dawson-like methods, widely used in naval-panel codes, therefore a second centered scheme can be used for the discrete operator on the free surface. Numerical results including the wave-pattern for a ferry along fifteen shiplengths are presented. @S0098-2202~00!01402-4#

Added Mass of an Oscillating Hemisphere at Very-Low and Very-High Frequencies

A floating hemisphere under forced harmonic oscillation at very-low and very-high frequencies is considered. The problem is reduced to an elliptic one, that is, the Laplace operator in the exterior domain with Dirichlet and Neumann boundary conditions. Asymptotic values of the added mass are found with an analytic prolongation for the surge mode, and with a seminumerical computation with spherical harmonics for the heave one. The general procedure is based on the use of spherical harmonics and its derivation is based on a physical insight rather than a mathematical one. This case can be used to test the accuracy achieved by numerical codes based on other formulations as finite or boundary elements