Simulation Of Complex Boundaries In Coupled Numerical Calculation Of Wave Force

The time-domain coupled model calculating nonlinear waves acting on marine structures is an important topic in ocean engineering. Using the coupled model to solve the wave propagation and the wave action on the offshore structures can avoid the limitation that scope of application is narrow, which is caused by simply using the potential flow model, viscous flow model or the Boussinesq equation model, etc. This paper study making the time-domain coupled model calculate the wave field acting on the marine structures that have more complex boundary. The whole computation domain is divided into inner domain and outer domain. The inner domain surrounding the cylinder is governed by the Laplace equation, which is solved by the finite element method. The other area is the outer domain and is governed by Boussinesq equations, which is solved by the finite difference method. Matching conditions on the interface boundaries are applied to couple the inner and outer domains.Firstly, introduce mesh generation technology of the finite element analysis software-ANSYS and apply it to grid division of inner domain of the cylinder model and ship model.Secondly, the nonlinear time-domain coupled numerical model is adopted to calculate the nonlinear wave pressure acting on a circular cylinder and wave surface elevation. Calculated values compared with the experiment values show that:compared to the situation of the short period(T=1.6s),the coupled computational model has satisfactory accuracy at the major period(T≥2.0s). In the case of short period (T=1.6s) the non-linear characteristics of wave aren't obvious, but at the major period (T=2.0s) they have a higher proportion. At the situation of large height(H=8cm),the second harmonic wave have larger values.Compared with the same wave height in smaller period(T=2.0s),the second harmonic of wave-front has larger amplitude and also has three to five times larger harmonic at the long period waves (T=3.0s). The non-linear characteristics of wave pressure isn't very clear compared to the case of wave elevation.Finally, apply the three-dimensional calculation model to calculate wave acting on the hull. Verify the applicability of the coupled model.