Fundamental Study on Floating Type Wave Absorber by the Finite Element Method

Abstract

The present paper deals with the diffraction problems of water waves due to a floating type wave absorber which consists of the plural vertical plates. The method of solution is based on the finite element method combined with the source distribution method. Namely, by a fictitious juncture boundary, a fluid domain is divied into both outer regionand inner region. The velocity potential for the outer region is given by utilizing the source distribution on the fictitious juncture boundary. On the other hand, the velocity potential for the inner region is determined by the finite element method. Numerical results which were applied to the plural vertical plates show that the zero reflection and complete transmission are possible, and the number of the occurrence of the complete transmission is in proportion to the number of the fluid colums between the plates. The wave exciting forces (X-direction) which were calculated by the plural vertical plates show that the wave excitationless frequency existed. The two plates with the external damping gave better effect of the wave absorption than the two plates in the vicinity of a wave length where the motion of the fluid column between the plates is resonant.