Numerical Simulation Of Nonlinear Ship Wave-making In Shallow Water

Modern ship is always sailing in the neritic sea,lakes and rivers where there are boundaries on the bottom or beside the ship,which called restricted water.Because of the flow around ship changed,the wave-making resistance in the above-mentioned water area will be different compared with it in deep water.When ship moves in static water,the ship attitude will change due to the unbalanced distribution of hydrodynamic pressure along the hull surface.Especially in restricted water,the trim and heave will be obviously.In the shallow water,the ship will touch the bottom with large sinkage and trim,which threating people's life and property security.There are vast sea areas,extended coastline,rivers and lakes in our country,so it has very important practical significance to accurately forecasting the wave-making resistance and ship attitude.The nonlinear method for ship waves based on the high order panel method is shown in the present paper.The combined free surface condition is adopted with all nonlinear terms remained.At each iteration,nonlinear free surface condition and hull surface condition are satisfied on real surface.The bottom boundary is satisfied by the method of images and the radiation condition is satisfied by shift the collocation pionts forward.Bspline surface interpolation is applied to original offsets data to automatically generate hull mesh during iterations.A preconditioned Generalized Minimal Residual method(GMRES)is employed to solve the resulting boundary integral equation in order to improve efficiency.Adoped the method mentioned above,the Fortran code is developed.The present method has been applied to both infinite and finite water depth ship wave problems.In the infinite water depth,the wave drag,sinkage,trim and wave profile of Wigley and S60 hull have been calculated and the numerical results are in good agreement with experimental data.In the finite water depth,the method has been applied for wigley hull wave drag and wave profile for varying water depth and speed and the effects of water depth to wave resistance and wave profile have been discussed.