【摘要】 文章使用直接时域理论和间接时域理论分别对船舶时域运动的时延函数进行了数值计算与比较。直接时域理论需要更多的计算时间与资源,相比之下间接时域理论的处理方式则更加简单快捷。数值结果表明间接时域理论在处理无航速和较低航速工况下则显得更加高效实用。基于间接时域理论,考虑非线性晃荡作用的船舶与浮式结构物的全局时域运动方程得以建立,其中非线性晃荡效应由粘性流理论来加以描述,波浪、船舶运动和液舱晃荡之间的耦合作用得以完整考虑。此方法分别使用势流和粘流分别描述外流场和内流场,具有很高的计算效率。文中对一艘LNG船在不同的来波下进行了一系列数值研究,数值结果和实验结果吻合良好。更多还原

【Abstract】 Numerical calculations and comparisons on retard-function for time-domain ship motions were conducted by using both DTM(Direct Time-domain Method) and FTTM(Frequency Transforming to Time-domain Method). DTM is a unified and self-contained theory that it needs heavy CPU times to obtain retard-functions, while it is easy and very quick by using FTTM. For the limitation of frequency range, numerical error may be uncertain and might occurs when FTTM was adopted. The numerical result indicates that FTTM is efficient and practical to handle hydrodynamical problems for ship motions without speed or with low speed. By using FTTM, global ship motion equations involving nonlinear sloshing forces were established in time domain, in which nonlinear sloshing flow behavior was described by using viscous flow theory. The interactions of wave, ship motions and tank sloshing were completely taken into consideration. This method has quite high efficiency since that it takes advantage of potential flow theory for outer flow field and viscous flow theory for inside tank flow field respectively. In this research, time domain sloshing coupled with LNG carrier with a wide range of incident wave frequencies was investigated experimentally and numerically.Both numerical and experimental results were agreeing well with each other.更多还原