Numerical study on wave loads and motions of two ships advancing in waves by using three-dimensional translating-pulsating source

A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course in waves. Two experiments are carried out respectively to mea- sure the wave loads and the free motions for a pair of side-by- side arranged ship models advancing with an identical speed in head regular waves. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more accurate than the traditional method based on the three dimensional pulsating （3DP） source Green function. Numer- ical resonances and peak shift can be found in the 3DP pre- dictions, which result from the wave energy trapped in the gap between two ships and the extremely inhomogeneous wave load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free sur- face and most of the wave energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on wave loads and free motions are significant. The present solver may serve as a validated tool to predict wave loads and motions of two ves- sels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.

近距两浮体间流体共振分析（英文）

目的：基于三维线性势流理论，通过在近距两浮体间的自由液面上引入“粘性耗散系数”，建立计及粘性影响的波浪中近距两浮体水动力干扰效应分析数值计算方法，以准确分析两浮体的干扰力及浮体间液面升高；并探讨“粘性耗散系数”的确定方法、两浮体间流体共振频率及共振模式的数值计算方法。方法：1．通过理论分析，在三维线性势流理论基础上，引入流体“粘性耗散”（公式2、10～12、18和19）以准确模拟近距两浮体波浪中的水动力及浮体间液面抬升；2．采用雷诺应力平均方程（RANSE）方法或试验方法确定“粘性耗散系数”（图2和3）；3．采用数值计算和理论分析的方法给出近距两浮体间的流体共振模式（图8）及共振频率估算方法（公式21～25）。结论：1．采用三维线性势流理论并引入流体“粘性耗散系数”可较为准确地计算得到近距两浮体波浪作用下的受力及浮体间液面抬升；“粘性耗散系数”可通过RANSE方法或试验方法获得；2．相比于其它因素（浪向角等），近距两浮体间的干扰效应受横向间距影响较大；3．采用类似于“月池”中流体共振频率分析方法获得的共振频率计算公式可用于估算近距两浮体间的流体共振频率，同时不同共振频率时浮体间的流体共振模式得到了数值计算结果的验证。