波浪作用下一种鲆鲽类方形网箱水动力特性数值模拟研究

针对鲆鲽类方形重力式网箱在纯波浪条件下的水动力特性,采用数值模拟的方法对鲆鲽类方形深水重力式网箱的主要部件——浮架系统、配重系统、锚碇系统进行了模拟。将模拟结果与实验结果进行分析比较表明,数模与物模各量值吻合良好,平均相对误差均不超过9%,表明数值模拟的方法能较好地模拟鲆鲽类方形深水重力式网箱的水动力特性。在此基础上,用数值模拟的方法,进一步研究了底框质量和网衣高度的改变对网箱各参数的影响,模拟结果显示,底框质量改变主要影响锚绳受力和底框倾角,底框质量从80 g升至100 g再升至140 g的过程中,锚绳受力平均增幅分别为13%和19%,同时增大底框质量有助于减小底框运动倾角,其平均降幅分别为8.8%和9.3%;网衣高度由20 cm增至30 cm后,锚绳受力平均增加15%,同时网衣的增高导致对浮架和底框的牵制作用加大,使得浮架和底框的运动幅度有所减小,降幅不超过10%。在以上研究结果的基础上,为鲆鲽类网箱的设计与优化提供了参考建议。

Numerical investigation of hydrodynamic properties of gravity cage for flatfish culture during exposure to wave action

We analyzed the hydrodynamic properties of a gravity cage for flatfish culture during exposure to wave action.We constructed a numerical model to simulate the hydrodynamic behavior of the float collar,the base frame system,and the mooring system,the primary sections involved in withstanding waved-induced forces acting on the net cage structure.We conducted a series of experiments to validate the numerical model.The numerical model appeared to predict the experimental behavior well(mean relative error was <9%),suggesting our model can be used to accurately predict the primary hydrodynamic behavior of gravity cages in waves.After validating the numerical model,we evaluated the effect of the weight of the base frame and the height of the net pen on mooring line tension and cage motion.The mooring-line tension increased by 13% and 19% and the inclination decreased by 8.8% and 9.3% as the weight of base frame increased from 80 to 100 g and from 80 to 140 g,respec-tively.Thus,increasing the weight of the base frame in favor of decreasing the inclination results in an increase in the tension on the mooring lines of ～15%.The values for these parameters decreased by <10% when the height of net pen was increased from 20 to 30 cm.The motion of the base frame was reduced slightly due to an increase in the forces acting on the float collar and the base frame of the cage net.Based on our observations,we offer sug-gestions regarding the design and optimization of cages for flatfish culture.