A computationally efficient approach to estimate design wave force on seawalls under large amplitude irrotational waves

Estimation of nonbreaking wave forces on seawalls for design is generally carried out through either empirical or analytical formulations with some inherent assumptions. Computationally intensive solutions, such as those based on Smooth Particle Hydrodynamics (SPH) and mixed Eulerian-Lagrangian (MEL) schemes, may not always be feasible for this purpose. In this paper, a numerical approach that employs Bernoulli's equation at the free surface and continuity equation over the fluid domain is proposed to accurately obtain the dynamic wave pressure. Subsequently, the wave forces on a rigid seawall are determined following the Froude-Krylov theory, with diffraction effects approximately accounted for by a horizontal force coefficient. The method is both computationally efficient and applicable to a wide range of irrotational wave propagation conditions, including large amplitude waves. The nonbreaking wave forces evaluated for a large amplitude travelling wave profile taken from literature are found comparable, but with some differences, to those obtained using the existing design standards. Hence, results from the proposed method for varying water wave propagation conditions are utilized to derive correction factors that can be applied to the existing stipulations in design standards for a more accurate assessment of wave forces for seawall design, without undertaking rigorous numerical computations.