Numerical Study Of Hydrodynamic Forces On A Turning Ship With Small Radius At Low Speed In Shallow Water

The working conditions of a ship turning at low speed and small radius with different drift angles in shallow water are common in navigational waters such as harbors and estuaries.In these water areas,the environment is complex,the ship is difficult to maneuver and the risk of an accident such as collision,stranding and grounding is very high.Accurately predicting the hydrodynamic forces on the ship in these water areas under different working conditions is of great significance for improving the navigation safety.In this thesis,the numerical method based on solving the RANS equations is applied to study the hydrodynamics of a ship turning at low speed and small radius with different drift angles in shallow water of different depth,and the software STAR-CCM+ is chosen as the numerical solver.Firstly,the method for motion simulation,the computational domain,the turbulence model and the mesh type are explored by comparative study.According to the results of the exploration,the rotating reference frame is selected to simulate the ship's turning motion,a moderately-sized fanshaped computational domain is used to simulate the rotary flow field,the SST k-? model to simulate the turbulence phenomenon,and the Trimmed grid to discrete the computational domain.Then,the selected numerical method is verified and validated.Finally,the numerical method is applied to simulating small radius turning motion under three working conditions: zero drift angles at different water depths,different drift angles in deep water,and different drift angles at different water depths.The hydrodynamic forces on the ship are computed,and the results are analyzed.It is found that the rotating reference frame method has the most efficient processing capability for simple rotary flow field.The computational domain,the turbulence model and the mesh type have great influence on the simulation results of the considered particular flow field.The numerical results show that the method selected in this thesis can better predict the hydrodynamic forces on a turning ship at low speed and small radius with different drift angles under different water depths.The results and analysis have a great reference significance for cognizing small-radius rotary flow field,and can also provide some theoretical basis for marine operation such as tug-assisted ship's rotation.