Numerical Simulation On Motion Response Of Moored Floating Body In Wave

Mooring system is an important part of floating structure,the study of the interaction between floating body and mooring lines plays a big role in evaluation of mooring performance and the overall design of the mooring system.In this paper,the interaction between floating body and mooring lines are studied by code development on an in-house CFD solver and using commercial software.The specific works are as follows.At first,catenary equation is adapted to mooring line with part lying on the seabed.Node equation of mooring motion is derived based on lumped mass method,both static and dynamic mooring analysis module are developed by the FORTRAN programming language.Static mooring analysis method ignores dynamic mooring line motion,which is solved by Newton iteration to get steady solution.A deep water mooring line is calculated by static mooring analysis accounting for current loads.The solution is compared with the results from OrcaFlex software to examine the code validity.And dynamic mooring analysis method is solved by using Newmark-β and Newton iteration,which is verified by comparison of the results with literature.6DOF motion equation is derived in moving coordinate system,which is solved by using 4 fourth-order Adams scheme and gauss elimination method.The 6DOF motion module is verified by comparison of the results with analytical solution.Numerical simulation is calculated to investigate the motion of a floating box in slide surge based on the in-house cut-cell CFD solver.The 6DOF motion module lays a foundation for the analysis of mooring floating body.Based on 6DOF module and mooring module,a weak coupled analysis method of floating body and mooring lines is proposed.That method is verified by a testing case of a floating breakwater,in which hydrodynamic forces are calculated through regular wave analytical equation.A 2D numerical wave tank is established by using the in-house CFD solver,and a regular wave case is used to examine wave generation and wave absorbing function.By using that NWT,the case of interaction between floating breakwater and regular wave is calculated.At last,time domain analysis of a parallel-connected FLNG and LNG carrier system is carried out.By examining the relative motions,hawser tension and fender deflection,the safety of side-by-side moored terminals are assessed.A CFD approach is applied to predict the appropriate current loads,which accounts for multi-body hydrodynamic interactions on current loads.It shows much higher precision than those current loads empirical formula.