Water wave scattering by a structured ridge on the sea bed

The propagation of plane incident waves over a long submerged uniform rectangular structured ridge protruding from the sea bed is considered. comprised closely-spaced array vertical barriers between which fluid allowed to flow. In addition height and width ridge, orientation thickness are adjustable design parameters. Particular interest centres negative refraction obliquely-incident waves, shown be possible provided extend sufficiently close surface. A key result that modulus reflection transmission coefficients symmetric functions wave heading barrier orientation. This implies perfect energy for thin elements at angles reverse orientation, extending Porter (2021) plate arrays any submergence. paper details two mathematical approaches solution problem, one general orientations other specific where special treatment resulting problem required. Numerical computations compare favourably with variety established results good agreement an existing shallow water approximation confirmed wavelengths.