| Tugboat assistance plays a significant role in ship berthing or unberthing. Tug-ship interactions which occur in tugboat operations will directly act on tugboat. Due to tug-ship interaction, tugboat likely becomes maneuveringly difficult and dangerous. So research on the tug-ship interaction is of great importance. It is also necessary to integrate the tug-ship interactions into the towage model in tug simulator.The main contributions of the thesis focus on the tugboat’s slipstream effect and ship-ship interaction, and are summarized as follows.1. The mathematical model for tug’s slipstream effect is estbabished based on least-square algorithm. F test is done for the mathmetical model, which demonstrates that the mathematical model is reasonable. The Matlab simulation results about the mathematical model can embody the effect of the tug’s slipstream.2. Ship-ship interaction on the tugboat is built based on potential-flow theory. Firstly, the source or sink is arranged on the tugboat and towed-ship to replace the ship hull disturbance to the incoming flow. The strength of the source or sink is arranged according to the geometry of the ship body. Secondly, the induced velocity of the tugboat and towed-ship are obtained on the basis of the arranged source or sink. Thirdly, the pressure around the tugboat body surface is caculated in accordance with the induced velocity by use of the Bernoulli equation. At last, the lateral force and yawing moment acting on the tug is caculated by Simpson integration.3. The simulation platform is established using the Visual C++6.0for testing. Three simulations are carried out in the thesis, namely, tugboat towing towed-ship forward motion, tugboat towing towed-ship yawing, and ship-ship interaction between tugboat and towed-ship. The former two tests are related to tug slipstream effect. The third test is about ship-ship interaction effect. The tests demonstrate the effectivness of the tug-ship interaction model. |
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