Radiation study of coaxial porous cylindrical structures for a given oscillation

Abstract

The paper uses the eigenfunction expansion method to investigate the radiation of coaxial porous cylindrical structures in the ocean for a given oscillation. The study of the coaxial porous cylindrical structures considers two cases: (1) a coaxial porous structure placed on the seabed, and (2) a floating coaxial porous structure. Based on the linear water wave theory and the eigenfunction expansion method, the equations for the velocity potential, the added mass, and the damping coefficient of the coaxial porous cylindrical structure are obtained. Darcy’s law is satisfied at the porous boundary. The continuity condition is satisfied between the fluid regions. The added mass and damping coefficient are calculated based on the velocity potential. The radiation results of the two cases are studied, and the influence of different parameters on the structures can be obtained. In addition, the porous parameters and radius ratio have a significant effect on the hydrodynamic coefficients (the added mass and the damping coefficient) of the structure, so the appropriate porous parameters and radius ratio can be selected to reduce the effect on the structure. The results in this paper provide clear information for the selection of appropriate parameters when engineering in offshore and coastal regions.