Diffraction de la houle sur des obstacles à parois verticales

Wave diffraction on vertical-sided piers

Ingénieurs au Centre de Recherches et d'Essais de Chatou (E.D.F.).

Résumé

It is proposed to calculate in a linear irrotational wave theory the forces acting on vertical-sided structures subjected to waves coming in from an infinite distance. The problem is solved by determining the diffracting wave potential and adding it to the incident waves, which is done in two phases, as follows: 1) Finding Green's function (Eqs. 1 to 5) ; 2) Determining the intensity of the sources to distribute over the obstacle. Green's "influence" function represents the singular potential created by a source. Source intensity is determined by expressing obstacle wall impermeability, which leads to a Fredholm integral equation. A numerical solution method for this equation has been applied with an IBM 70 94 computer. The results were first compared with Havelock's analytical solution for a circular pier (Fig. 3), which confirmed the accuracy of the numerical solution. Figures 4 and 5 show results for piers formed by envelopes of two and three circles respectively. Figures 6 and 7 refer to elliptical and dihedron-ended piers, and Figure 8 is an example with obstacles in the form of three separate circular piers.