近距两浮体间流体共振分析（英文）

Modeling of fluid resonance in-between two floating structures in close proximity

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。

In this study, we conducted numerical simulations of fluid resonance in-between two floating structures based on potential theory assessing the effect of fluid viscosity by including the artificial damping force. The numerical results of two adjacent Barges systems and Barge ＆ Wigley systems were compared with experimental data of those of the viscous fluid mod- el based on Reynolds average Navier-Stokes equations （RANSE）. It can be observed that the conventional potential flow model （without artificial damping force） significantly over-estimated the wave height and forces around the resonant frequencies. Re- sults of the present method with an appropriate damping coefficient supported the available data, confirming the importance of the viscous damping effect on strong hydrodynamic interaction between the floating structures. Furthermore, influences of lat- eral clearances, wave heading angles, and ships＇ motions on the wave surface elevations were analyzed. Validation and applica- tion of methods to estimate the fluid resonant frequencies and modes were also conducted. Generally speaking, Molin＇s simpli- fied theory can give an accurate estimation of resonant frequencies and serve as a practical tool to analyze the fluid resonant phenomena of gaps in-between a two Barge system and Wigley ＆ Barge system in close proximity.