Numerical Evaluation of Capsizing Probability in Quartering Seas with Split Time Method

摘要

The paper discusses a split-time method to estimate the probability of capsizing of naval ships in irregular quartering seas. The calculation of the probability of capsizing presents. a formidable mathematical problem as the roll period and mean time to capsizing are practically incomparable values, which presents the problem of rarity. The split-time method attempts to solve the problem of rarity by separating the solution domain in two or more parts, each of which can be solved separately and efficiently using numerical simulations. The solutions are combined through upcrossing theory and initial conditions, with a careful consideration of the distribution of initial conditions at upcrossing. The use of advanced, physics-based body- nonlinear numerical simulations allows the method to directly evaluate a ship's changing stability as it moves in waves and to consider unconventional as well as conventional hull. The paper also discusses some ideas on how the split-time method can be applied to the probability of capsizing due to broaching, and reviews a study of the ability of potential flow based simulations to predict the phenomena of surf-riding and broaching in regular waves.