NUMERICAL INVESTIGATION OF NONLINEAR WAVE INTERACTION WITH A SUBMERGED OBJECT

Submerged objects are widely occurred in ocean and coastal engineering. Their presence influences the neighbouring flow field and even generates higher harmonic waves. A two-dimensional fully nonlinear numerical wave flume, based on a time-domain higher-order boundary element method is developed to investigate nonlinear interactions between regular waves and a submerged object. The incident wave is generated by the inner-source wavemaker. Fully nonlinear kinematics and dynamics boundary conditions are satisfied on the transient free surface. A mixed Eulerian-Lagrangian technique combined with the fourth order Runge-Kutta scheme is used as the time marching process. A four-point method is used to separate bound and free harmonic waves. The proposed model is verified against the experimental and other numerical data for nonlinear waves scattering by a submerged trapezoid and a submerged horizontal cylinder, respectively. Numerical tests are performed to investigate the effects of submergence and characterised length of a submerged object, static water depth on the high free harmonics.