The Research Of Hydrodynamic Characteristics And Deformation Of Net Panels Under Currents Action

At present,the development of aquaculture in China is receiving more extensive attention.Mariculture as a relatively heavy part of the aquaculture field,is constantly playing an important role.At the same time,the shrinkage of marine near-shore space and environmental pollution in the increasingly aggravated,the offshore ecological environment is facing a great threat.Therefore,the protection of the marine ecological environment is increasingly valued,and seawater aquaculture,which is closely related to it,urgently needs to be transformed and gradually shifted towards open deep-sea aquaculture.As one of the important components of aquaculture nets,the nets are responsible for defining the fish activity area,ensuring water exchange and providing reliable growth habitat for fish.It has a significant impact on the dissolved oxygen content in the net cage.Meanwhile,in the complex environment of deep sea,the nets are subjected to the scouring effect of the current.Especially,after the deformation of the flexible net,it will cause the effective volume inside the cage to decrease,and there may be a risk of net tearing.So it is crucial to clarify the hydrodynamic and deformation characteristics in the flow field for the design of nets.Based on numerical and experimental methods,this dissertation conducts an analysis of the flow field and hydrodynamic characteristics of rigid planar nets.The accuracy of the mesh grouping method in the fluid-structure coupling of net panels is analyzed.Then,the deformation characteristics of net panels under different angles of attack and flow speeds is investigated based on the fluid-structure interaction method.Firstly,this dissertation briefly introduces the research background and current situation of net cages and nets.Secondly,the basic theory of numerical simulation is introduced,including the geometric parameters of nets,the mathematical theory of numerical simulation methods,the selection of suitable turbulence models,and the verification of grid independence of flow field characteristics analysis.Then,the flow field and hydrodynamic characteristics of rigid net panels are analyzed.Next,based on a circulating water tank experiment,the differences in drag and drag coefficient of different types of nets are compared when the attack angle and Reynolds number change.Finally,based on the fluidstructure interaction method,the experimental values of the previous chapter are verified,and the flow field and deformation characteristics of the overall net under the mesh clustering method are further studied.The mesh grouping method is combined with coupling calculation to solve the problem of a large number of meshes in fluid calculation.The stress distribution and deformation characteristics of net panels are analyzed.It plays a reference role in the design of aquaculture net cage in engineering.