波流逆向和同向作用下重力式网箱水动力特性研究

A numerical study on dynamic properties of the gravity cage under parallel and counter wave-current conditions

深水重力式网箱在风浪和海流作用下的动力响应研究,是外海养殖网箱设计与制作的基础。为研究波流逆向作用于深水重力式网箱时的运动响应和锚绳力与波流同向时的差异,基于波浪作用通量守恒和Stokes3阶波理论数值模拟波浪在水流中的变形和综合波流场;采用质量集中法和刚体运动学原理,建立重力式网箱数学模型;考虑不同设计流速和波浪组合,利用数学模型得到在波流逆向和波流同向作用下重力式网箱的锚绳力,浮架运动和网箱剩余体积的结果。结果显示:波流同向时的锚绳张力比波流逆向时大;波流逆向时重力式网箱体积剩余系数最小值比波流同向时的大。因此,波流同向对重力式网箱的破坏比波流逆向严重。

Technical solution of wind wave and flow resistance of cages is the key for open-sea aquaculture. This study aims to discuss the difference of gravity-cage motion response and mooring-line force between parallel and counter wave-current conditions. In this study, based on the conservation law of wave action flux？ and Stokes3 wave theory, numerical simulation of wave deformation in current and composite wave-current flow field was simulated; Based on lumped mass method and the principle of rigid body kinematics, a numerical model of gravity-cage was developed. Considering the different combination of design flow rates and waves, the mooring-line force, floats motion and volume holding coefficient of net cylinder of the gravity - cage were calculated under parallel and counter wave-current conditions based on the numerical model. The numerical results strawed that mooring -line force was larger under the parallel wave-current than that under the counter wave-current; the minimum value of volume holding coefficient of net cylinder was larger under the counter wave-current than that under the parallel wave-current. In conclusion, the destruction effect under the parallel wave-current on gravity-cage is more serious than that under the counter wave-current.