Wave diffraction from a concentric truncated cylinder system with a porous ring plate fixed inside

The diffraction problem of a concentric truncated cylinder system with a porous ring plate fixed inside is studied in the framework of linear potential theory. The system consists of a porous exterior cylinder and an impermeable interior cylinder, which are connected by an impermeable top and bottom plate, and a porous ring plate arranged below the free surface. Darcy’s law is applied to the porous boundaries under the assumption of fine pores. The velocity potential of the whole fluid domain is analytically derived by the method of variable separation and eigen-function expansion. The hydrodynamic loads of the system are obtained by integrating the pressure on the wet surface. The calculation results of the present paper are compared with the previous works with similar models to verify the correctness of the model. The effect of the dimensionless porous effect parameter of the ring plate and of the exterior cylinder, the draft–depth ratio of the ring plate, the draft–depth ratio of the system, the ratio of the interior and exterior radii are discussed. The results show that appropriate permeability and structural scale parameters can improve the hydrodynamic performance of the structure, which will provide directive guidance for engineering design.