Numerical Study On The Influence Of False Bottom On The Hydrodynamic Test Of Ship Model

When the ship is sailing in shallow waters,the difficulty of handling becomes greater and the drag increases,and the resulting squatting phenomenon may seriously cause the ship to hit bottom.False bottom equipment is usually used to change the water depth in the model test of studying shallow water effect.The 29_thITTC manipulation committee held a special discussion on this issue and proposed that scholars conduct research and discussion on this issue.Therefore,the numerical study of false bottom in this paper is of practical significance and demand.CFD software is used to simulate the viscous flow of KVLCC2 standard module with false bottom in shallow water,by solving the RANS equation,the effect of false bottom width on ship hydrodynamic force under different drift Angle draft ratio at different speeds was compared.Firstly,the experimental results of INSEAN vessel pool are verified and compared by numerical method.The turbulence model suitable for low-speed oblique navigation in shallow water is selected from the two turbulence models.Then the mesh convergence analysis is carried out.After verifying the reliability of the numerical method,two kinds of false bottom test schemes,the false bottom test scheme with the ship and the fixed false bottom test scheme are simulated and analyzed respectively.The feasibility of the two schemes is compared and the influence law of the false bottom equipment on the hydrodynamic force of the test operation is obtained.In this paper,an overlapping grid scheme is adopted for the numerical simulation of fixed false bottom test,which improves the computational efficiency and provides a good fitting degree for the subsequent numerical study of fixed false bottom.By comparing the two kinds of false bottom schemes,a more practical fixed false bottom test scheme is selected,and some reasonable Suggestions on the length and width of false bottom equipment are given.