ABSTRACT

Maritime rescue is usually dangerous and difficult. In order to ensure the safety of rescue, a two dimensional simulation of two Wigley in numerical wave tank is made to predict the ship motion. Base on the Navier-Stokes equations, VOF model and overset method, the motion of two ships was simulated in time domain. The effect of different distance of two ships, different wave period and different wave height is researched. It is found that the increase of distance and wave height will increase the amplitude of the ship motion.

INTRODUCTION

When the rescue ship assistant accident ship, such as transporting the wounded, delivering the supplies or carrying out some other operation, two vessels would have to come to a relatively close proximity. The relative location of two ships is similar to the FPSO–shuttle tanker system (Koo, Kim,2005), however both of the ships are unconstrained. In the situation that the weather is terrible, the progress is actually dangerous for the ships would move violently. In order to avoid the accident, it is necessary to predict the motion of ships.

The multiply body question has been searched for a long time. Hong and Kim (2005) proposed a higher-order boundary element method (HOBEM) and certificate it by experiment. The result shows that the simulation based on HOBEN has a good agreement with the experiment result in ship motion and wave drift force except for the wave drift force in the narrow gap between two ships which has a strong interaction due to Helmholtz resonance. Chen (2005) proposed the damping lid method. He added a dissipative term in the free surface boundary condition inside the gap to get a better accuracy in wave drift of the narrow gap of two ships. After that, studiers start to solve the problem in time domain. Nam and Kim (2016) simulated the berthing progress of the FPSO and shuttle tank in time domain. By using re-mesh algorithm method, they make the calculation more efficient. Pessoa and Fonseca (2016) studied the second order low frequency relative motions between the vessels and related mooring line tensions. Yue，Kang et al (2020) discuss the situation that one FSRU connected with the LNGC by cables. Moreover, the uncertainty analysis is discussed by experiment two model ship in towing tank (Qiu, Meng, Peng and Li,2019).