Numerical investigation of side-wall effects on the seakeeping performance of a ship advancing in waves

摘要

During seakeeping tests of a ship model in a towing tank, the hydrodynamics will show discrepancies when compared to the open-sea results because of side-wall effects. Here, a three-dimensional panel method based on a Rankine-type tank-wall Green function is proposed to solve this problem. This tank-wall Green function, which satisfies the non-penetration condition on the side walls, is in the form of an infinite series, which has slow convergence. Therefore, an approximate computation method is established, and this is found to have satisfying efficiency and accuracy. The present numerical results are compared to the corresponding experimental results from a floating spheroid of beam-length ratio 1/5 and a Lewis-form ship, both advancing with forward speed at Froude number 0.1. Good agreement between the test measurements and the numerical results is obtained in all cases, indicating that the present panel method is useful and applicable. According to the propagation characteristics of the three-dimensional translating-pulsating source Green function, an approximate discrimination method is proposed for identifying side-wall effects. The present numerical method can be further extended to investigate the interactions between side-wall effects and shallow-water effects.