Research On Automatic Mesh Generation And Calculation Strategy Of Ship Roll Damping Based On OpenFOAM

Rolling motion in ship stability affects the safe navigation of ship in waves.Damping prediction of ship rolling motion is a key factor in predicting ship motion response.Correct estimation of ship roll damping and accurate prediction of ship motion response will greatly guarantee the safe navigation of ships.Based on the characteristics of ship’s rolling in still water,it can be used to study the ship’s motion response in waves.Therefore,this paper uses OpenFOAM,an open source software,to carry out the virtual test of ship’s rolling damping based on the characteristics of its meshing and calculation parameters.The open source sofOArare OpenFOAM 1s used for numerical simulation,and the grid can be automatically divided by preset parameters without importing external software.Firstly,based on grid generation and referring to the guidance of ITTC,the strategy of automatic grid generation for ship rolling damping virtual test is given,which can automatically divide hull grid and computational domain grid for given ship type.The virtual test cycle is greatly shortened.In the process of mesh generation,the number of meshes and the minimum mesh size are controlled to improve the computational efficiency of virtual test,and the addition rate of boundary layer meshes at the bilge keel of ship hull is improved by parameter optimization,and the quality of virtual test meshes is improved.Based on the strategy of grid automation for virtual test,roll damping of container ships without bilge keel and container ships with bilge keel are studied in this paper.The detailed flow chart of virtual roll damping test with OpenFOAM is described,and the setting strategy of calculation parameters is given.By studying the influence of relevant parameters in calculation strategy on the stability and accuracy of virtual test results,the general rules of the influence of discrete scheme and dynamic mesh relaxation factor on simulation results are analyzed,and the applicable range of virtual test for rolling damping is expanded.Finally,the reasons for the inaccuracy of the simulation results are analyzed Fnom the point of view of the change of the damping components in the rolling process,and the measures to prevent the divergence of the virtual test calculation are studied on the universality of the numerical simulation easy to diverge at high speed.