CFD-FEM numerical simulation analysis of ship whipping response under extreme sea conditions

Objective This paper investigates the coupling effect of ship nonlinear wave load and transient high-amplitude slamming load in view of the whipping response of ships under extreme sea conditions.

Methods A two-way computational fluid dynamics-finite element method (CFD-FEM) fluid-structure interaction method is used to carry out the numerical simulation of an S175 container ship, and the results are compared with the test results and 2D linear strip theory. The testing of a segmented ship model with a variable cross-section elastic backbone is carried out, and the analysis of the bow's slamming load and high-frequency nonlinear whipping characteristics is undertaken based on the two-way CFD-FEM fluid-structure interaction method. The results are then verified through comparison with the model test.

Results The influence of wave slamming load on the whipping response of the bow cannot be ignored. The second order high-frequency component induced by whipping accounts for 59.86% of the low-frequency wave bending moment in sea state 6.

Conclusions The proposed two-way CFD-FEM fluid-structure interaction method can calculate the whipping response accurately. The nonlinear wave-induced load and dynamic structural response of the ship under extreme sea conditions are affected by the transient slamming load of the bow. In conclusion, the high-frequency whipping response should be taken into consideration in the safety design and assessment stages of ship structures.