Numerical Simulation Of Wall Effect Based On CFD

With the increasing of the ship dimensions, many waterways and the harbor waters are becoming narrower relatively, which are restricted waters. When navigating in these waters, the hydrodynamic force and moment acting on the ship will change significantly. Many experts and scholars have done a lot of research on it. On the basis of previous studies, considering the viscous of flow field, the numerical simulation of wall effect in restricted waters are carried out in this thesis with the technology of overlap grid.With the rapid development of computer technology, CFD (Computational Fluid Dynamic) is more and more widely used in ship hydrodynamics research. As the continued success of the calculation of ship viscous resistance, people begin to explore the numerical study of the ship maneuverability with considering the fluid viscous. Based on the CFD theory, the numerical simulation of wall effect has been performed by solving the RANS (Reynolds Averaged Navier-Stokes) equation. In this thesis, the study object is series 60 ship model. PISO (Pressure Implicit with Splitting of Operators) arithmetic is used to disperse the N-S equation. The turbulence model is SST k-ω model with the technology of overlapping grid and single level set method to simulate the free surface.Adopting the above method, the numerical calculation of series 60 ship model has been carried out respectively in coastal deep and shallow waters. Firstly, it is assumed that the ship is still and the directional flow is setting. The calculated results including ship resistance coefficient, lateral force coefficient and torque coefficient are compared with others’and the calculation results agree well with others’. Then release the degree of freedom of sway, heave and pitch and calculate the motion of ship. The lateral displacements of different distance to bank are obtained and the effects of speed on the lateral displacement are analyzed. Also the changes of the pressure distribution on the ship hull of different speed are analyzed.The overlapping grid technique adopted by the thesis has a great advantage. On one hand, this technique simplifies the generation of mesh; on the other hand, there is no need to regenerate new grid when ship moves, as long as it generate new grid interpolation information, which greatly reduces the workload and the amount of computation. The higher computational accuracy is the precondition of the usage of the technique. The calculation method of this thesis can be as reference for the further study of ship maneuverability in restricted waters. The calculation results can provide certain reference for the deck officer and pilot; it can also put forward some theoretical suggestions for the dredging and widening of waterways.