Study on Safety of Ship Navigation in Narrow Waterway

众所周知，船舶之间或船舶与岸壁、桥墩之间的水动力相互作用力对船舶操纵特性有很大影响。了解这些相互作用力的特点对于确保航行船舶的安全是非常重要的。在此基础上，提出了基于细长体理论的水动力相互作用力的理论预测方法，并对船舶在码头附近航行时的操纵运动进行了数值模拟。根据数值计算的结果，当船的侧向距离小于0.7L时，船体存在与桥墩相撞的危险。针对船舶低速大漂角运动时作用在船体上的水动力主要由横流阻力分量控制的特点，提出了基于旋涡脱落模型的船体横流阻力预报方法。结果表明，该预报方法能较准确地预报横流阻力沿船长的纵向分布，并利用预报的水动力建立了避碰系统，并通过考虑人为因素的数值模拟研究了该系统的有效性。

It is well known that hydrodynamic interaction forces between ships or between ship and bank wall or pier have much influence on characteristics of ship manoeuvrability. It is important to know the characteristics of these interaction forces to insure safety of sailing ships. Then we developed theoretical prediction method for the hydrodynamic interaction forces based on the slender body theory and carried out numerical simulation of manoeuvring motion of ships sailing in the proximity of pier. According to the results of numerical calculation, there is a danger that the ship will collide with the pier if the lateral ship distance is less than 0.7 L.We also developed prediction method for cross flow drag acting on a ship hull based on the vortex shedding model because component of cross flow drag dominates the hydrodynamic force acting on ship hull when ship is moving with large drift angle at low speed. It is shown that longitudinal distribution of the cross flow drag along the ship length can be predicted with comparatively comparatively high accuracy using the presented prediction method.Furthermore we presented collision avoidance system using the predicted hydrodynamic forces and investigated effectiveness of the system by numerical simulation considering human factor.