Wave-induced oscillations of submerged horizontal plates are studied by conducting laboratory experiments and by developing theoretical and computational models. These models include a linear solver based on the Green-function method, a nonlinear model based on Green–Naghdi wave equations, and a model based on computational fluid dynamics. The submerged horizontal plate oscillates in the vertical direction due to oscillatory wave loads. Oscillations of the plate are controlled by the use of a spring-damper system. Laboratory measurements and the models provide quantitative information on (i) how oscillations of submerged plates vary with wave conditions, plate characteristics, and the control system and (ii) how different models using different levels of assumptions predict the wave-induced oscillations. Particular attention is given to energy-production applications of the submerged oscillating plate, and discussion is provided on how the oscillation height and velocity vary with its initial submergence depth, stiffness of the attached spring, and the strength of the viscous damper. It is found that the oscillation varies almost linearly with the wave height, but nonlinearly with the wave period, initial submergence depth of the plate, damping, and the spring stiffness. Overall, it is found that nonlinearity plays an important role in this problem, while the effect of viscosity is negligible.

We consider a horizontal, submerged plate in shallow water that is allowed to oscillate in the vertical direction due to the wave loads. The plate is attached to a linear spring and damper to control the oscillations. The focus of the study is on the transformation of the wave field by the submerged oscillating plate. To estimate energy scattering, wave reflection and transmission coefficients are determined from four wave gauges; two placed upwave and two placed downwave of the oscillating plate. The flow is governed by the nonlinear Level I Green-Naghdi (GN) equations, coupled with the equations of the vertical oscillations of the plate. Time series of water surface elevation recorded at gauges upwave and downwave of the plate obtained by the GN model are compared with the available laboratory experiments and other data, and very good agreement is observed. Wave reflection and transmission coefficients are then determined for a range of involved parameters, including wave conditions (wavelength and wave height), initial submergence depth of the plate, plate length, and the spring-damper system attached to the plate. It is found that a submerged oscillating plate can have a remarkable effect on the wave field, and that nonlinearity plays an important role in this wave-structure interaction problem. Discussion is provided on how the wave reflection and transmission coefficients vary with the wave conditions, plate characteristics, initial submergence depth and spring-damper system properties.