Elastic Bottom Effects on Ocean Water Wave Scattering by a Composite Caisson-Type Breakwater Placed Upon a Rock Foundation in a Two-Layer Fluid

Abstract

The association of oblique surface gravity waves with a caisson-type multi-chamber porous breakwater fitted with a perforated front wall in a two-layer fluid is studied in finite ocean depth with an elastic bottom. This study focuses on the influence of porous parameters of the interface-piercing structure on wave attenuation in surface and interfacial modes. The flexural gravity wave motion establishes the influence of the elastic bottom. The reflection coefficients for waves in both modes are evaluated to show their effects on the free surface and interface elevations and the waveloads. Consequently, the appropriateness of various configurations of the structure on the wave scattering is studied. Due to wave dissipation by the structure, less waveload is detected on the stiff wall and less elevation is noticed in the porous zone. The structure’s multi-chamber division allows it to have more dissipative and reflective properties. Adjustment of the structure’s height, breadth, and porous parameter leads to achieving good amount of wave reflection and maximum energy dissipation. An optimal width can be determined for a suitable configuration of the structure so that a breakwater can be built with an acceptable level of reflection and dissipation characteristics. The shear force and bottom deflection show how elastic parameters of the sea-floor affect wave scattering.