LINEAR AND NONLINEAR WAVE FORCES EXERTED ON A SUBMERGED HORIZONTAL PLATE

Linear and Nonlinear wave forces exerted on a submerged horizontal plate are studied using the method of matched eigenfunction expansions for velocity potential together with the perturbation technique up to second order. Energy damping coefficients are introduced in the formulation to incorporate the effects of vortices and wave breaking. The theoretical results are compared with experimental data to obtain validity and limits of the second-order solution. The theory with proper energy damping coefficients can well simulate the wave forces even when wave breaking occurs over the plate. The second-order oscillatory wave force is relatively small as compared to the first-order one, while timeindependent, steady wave force becomes comparable with the first-order one at small relative water depth and its direction is always upward.