Numerical study on a KVLCC2 model advancing in shallow water

Due to the effects from the bottom of the waterway, advancing ships will sink deeper in shallow water than in deep water. This is known as squat effect, which increases with the speed of the vessel. The aim of the present paper is to provide a numerical method to predict the shallow water effects. The 3-D boundary element method is firstly applied to simulate a KVLCC2 model advancing in confined water. The wave-making resistance, as well as the sinkage and trim are calculated at different water depths. In order to verify the predictions from BEM program, CFD calculations in deep water will also be conducted and compared. Special efforts are made to calculate the wave elevations. The wave profiles at different water depths and distances are calculated. The comparisons between shallow water and deep water, as well as between the BEM and CFD programs, are also discussed in the present paper. Additionally, some comparison of the wave profiles with available experimental results is presented for validation of the approaches

Investigation of side wall and ship model interaction

Due to the existence of the side wall of the towing tank, the measured hydrodynamic forces would present some discrepancies compared to the open sea results. This phenomenon is referred as side wall effect. The object of the present study is to investigate the parameters which determine the side wall effects. The method used in the present study involves a 3D panel method based on Rankine type Green function. A ship advancing in a towing tank with parallel side walls is simulated and the numerical results are validated against model test results carried out by Kashiwagi and Ohkusu (1991). The parameters including wave frequency and forward speed which determine the side wall effects are discussed

Prediction of ship-lock interaction by using a modified potential flow solver

Ship-lock interactions are very difficult to predict. The hydrodynamics of ships entering (or leaving) a lock is always accompanied with shallow water and bank effects. When a ship enters or leaves a lock with a closed end, a so-called piston effect will be provoked due to the translation waves trapped in the gap between the ship and the lock door. Meanwhile, as the water is accumulating or evacuating in a lock with closed end, a return flow will be generated. The nature of the complex hydrodynamics involved in ship-lock interactions have not been fully understood so far and it is very challenging to develop a mathematical model to predict ship hydrodynamics in a lock. In the 4th MASHCON, the author presented his original simulation results of the hydrodynamic forces on a ship when it entered a lock based on a potential flow solver MHydro. A very large discrepancy was found between the numerical results and experimental measurements. It was con-cluded that the potential flow theory failed to predict the hydrodynamic forces on a ship when it entered a lock. Over the past two years, the author has continuously worked on ship-to-lock problem and proposed amodified potential flow method by adding a proper return flow velocity to the boundary value problem. The results showed the modified method could predict the resistance and lateral forces very well. However, it failed to predict the yaw moment due to the flow separation at the lock entrance

Double doppler shift theory on water waves generated by the translating and oscillating source

Paper deals with the development of double Doppler shift theory and application of double Doppler shift theory on the prediction of water waves generated by a translating and oscillating source