Research On The Numerical Simulation Of The Wave Flow Field In The Grid-type Cage

Global population growth is increasing demand for fish and other seafood,while offshore fisheries are degraded and wild fish stocks are depleted.In order to make up for the huge difference between the market and demand,aquaculture industry continues to expand to the deep sea,cage aquaculture has gradually become the most common deep sea aquaculture mode.The net is an important part of the deep sea aquaculture cage,which plays an important role in preventing fish escape and maintaining the water exchange between the cage and the outside world.However,due to the late development of the cage related technology in China,there are few studies on the interaction between the net and the wave flow and the wave flow field inside the cage.In view of the above situation,numerical simulation is carried out by using computational fluid dynamics software STAR CCM+.The porous media model is used to simulate the net,and the corresponding porous media model parameters are analyzed,so that the porous area can have the same effect as the real net.A numerical model was established for the interaction between net and the flow field and wave field.Based on the model,the influence of net on the propagation of wave flow field was studied.Compared with the previous model experimental results,the effectiveness of the net model in porous media was verified.Then,the internal wave flow field of the grid-type cage is studied,and the numerical simulation results are compared with the experiment results to verify the correctness of the numerical simulation method.Based on the calculation results of the net cage wave flow field,the load of the net grid structure in the wave flow field is analyzed.The content of this paper is mainly divided into five parts: The first part is the introduction,mainly introduces the relevant background significance of this research and the progress of relevant research at home and abroad;The second part mainly introduces the numerical methods adopted,including the governing equation,the principle of porous media model simulation net,free surface capture method and numerical simulation method of waves;The third part mainly verifies the correctness of the porous media model by comparing with the previous experiment results,obtains the porosity,inertial resistance coefficient and viscous resistance coefficient of the net used in this paper.The force of the single and double nets in the wave flow field,the blocking effect of the net on the flow field and the influence on the wave propagation are also analyzed.The fourth part builds the whole cage model,studies the interaction between the cage and the wave flow field,compares the numerical simulation results of the wave flow field inside the cage with the experimental results,analyzes the error between the numerical simulation results and the experimental results.The reason for this is that the load on the grid structure with or without net covering is studied.Finally,the paper summarizes the research results and shortcomings.