Improved prediction of the threshold of surf-riding of a ship in steep following seas     

Wan Wu  Kostas J. Spyrou 《Ocean Engineering》2010,37(13):1103-1110

An extended version of Melnikov's method is implemented in order to predict more accurately the threshold of global surf-riding for a ship operating in steep following seas. The key advantage of the proposed method is that it overcomes the limitation of small damping and/or small forcing that are intrinsic to the implementation of the standard Melnikov's method. A reference ITTC ship is used here by way of example and the result is compared to that obtained from standard analysis as well as numerical simulations. Because of the primary drawback of the extended Melnikov's method is the inability to arrive at a closed form equation, in this work the authors arrive at a “best fit” approximation to the extended Melnikov numerically predicted result.  相似文献   

Simplified model for predicting the onset of parametric rolling     

S. Surendran  S.K. Lee  K.H. Sohn   《Ocean Engineering》2007,34(3-4):630-637

The world container fleet shows the fastest growth of any ship type. The infrastructure for loading and unloading container ships are also growing in many ports around the world. Such a trend is due to the fact that the containerized transportation is becoming more and more attractive due to many factors. The increasing demand in container transportation is met by use of more number of container ships including Post-Panamax and Malacca-max containers. Loss of containers in seas and accidents of container vessels are reported from many parts of seas. New generation containers are severely hit by parametric rolling. Pure loss of stability, due to exponential increase of roll in either broaching—to or head sea conditions, is called parametric rolling, is subjected to rigorous investigation by many researchers. Algebraic expression based on well known Duffing's method is proposed for solutions in parametric rolling. The variation in GM and damping values from trough to crest conditions associated with bow flare immersion and emergence in head sea conditions with pitch resonance with the heading waves are said to be the prime reason for parametric rolling. A simple model to predict the beginning of parametric rolling is described in this paper.  相似文献