Interaction of Finite Amplitude Waves with Platforms Or Docks

Abstract

Interaction of finite amplitude non‐linear water waves with platforms or docks in constant depth or variable depth medium has been studied theoretically and numerically. Wave uplift forces as well as wave transformation characteristics have been obtained for various conditions. In order to conveniently treat the moving free surface, an isoparametric mapping technique is used to transfer the fluid region and its boundaries into a regular domain. A Galerkin finite element model is developed to model the transformed fluid domain. The resulting discrete equations are solved iteratively by using adaptive line successive over relaxation (SOR) method. Artificial viscosity is introduced in both the dynamic and the kinematic free surface equations to dampen out the free surface oscillations in the front region of the platform or the dock. The Runge‐Kutta method is employed to integrate the time variation in the nonlinear free‐surface equations. The computed time‐history of the total hydrodynamic force per unit width of the platform placed above the horizontal bottom compares quite well with the available experimental data. For the sloping bottom, some time‐history of the total hydrodynamic forces on platforms and docks are also computed to evaluate the effects of the sloping bottom. The sloping bottom significantly increases the uplift forces on platforms or docks.