Numerical investigation of wave radiation by a vertical cylinder using a fully nonlinear HOBEM

Abstract

A time-domain higher-order boundary element method (HOBEM) is developed to simulate fully nonlinear wave radiation by a forced oscillating structure. On the free surface, a Mixed Eulerian–Lagrangian (MEL) technique is employed in the time marching process, and mesh regridding and interpolation are applied to avoid possible numerical instability. An artificial damping layer is distributed on the outer part of the free surface to prevent wave reflection from the far-field boundary. For the calculation of wave loads, some auxiliary functions are used, instead of directly predicting the time derivative of the velocity potential. The developed model is applied to simulate a truncated vertical circular cylinder undergoing forced heave, surge or pitch motions, respectively. A series of higher-harmonic force components on the cylinder are derived by the Fourier Transformation. The added-mass and radiation-damping coefficients of the cylinder are also obtained from the least-square method. The simulated results are compared with the experimental and numerical results of other researchers. The present results are in good agreement with the experimental and other fully nonlinear results, while different with the linear and second-order solutions.