穿浪型雙體船在縱波中運動之時程模擬

The Time Simulation for the Motion of the Wave-Piercing Catamaran Ship in Longitudinal Waves

本文主要是利用三維源點分佈法於時程領域中，來模擬穿浪型雙體船於縱波中之運動，並檢視其降低縱搖運動之功能。穿浪型雙體船是於一般雙體船中增加一中央船體，當船體在大運動之狀況下，中央船體預期會適時提供一恢復力，以期達到降低雙體船之縱搖運動反應。文中使用小板法並以三維脈動型源點求解該船於頻率領域下，不同吃水深度之各項流體動力係數，再將求得之各項流體動力係數分別整合成一隨吃水變化之資料庫函數。接著利用四階Runge-Kutta數值解，模擬出該船於時程領域下之起伏與縱搖運動；並將該船之中央船體移除，比較該船有無中央船體之運動，以探討中央船體之實際作用。根據本文結果，發現在某些頻率下，當穿浪型雙體船高速行駛於大波浪中的時候，中央船體確可達到降低雙體船之縱搖運動反應。 In this study, the three-dimensional source distribution method in time domain was used to simulate the motions of the wave-piercing catamaran ship in Longitudinal waves. The wave-piercing catamaran ship is a catamaran ship with a central bow hull body which is expected to provide the extra restoring force and hydrodynamic force to reduce the pitch motion in large waves. The three-dimensional pulsating source based on panel method is used to calculate the related hydrodynamic coefficients with respect to different drafts in the frequency domain, which can be applied to establish the data base for the time domain calculation through the 4th Runge-Kutta method. From the comparisons with the conventional catamaran ship, we find that the central bow hull body of wave-piercing catamaran ship indeed works well on the pitch motion reduction at some specific wave frequencies, especially while the ship sail with high speed in large wave. Therefore the validity of the central bow hull body of the wave-piercing catamaran ship can be proved.