Net And Net Cage Effects On Wave Propagation And Its Hydrodynamic Behaviors

In recent years,with the demand for seafood increasing rapidly,fishery resources is becoming less and less.Besides,the rapid growth of economic has brought serious pollution to offore environment.The rapid increase of demand for seafood and ecological environment getting worse, leading to a result of demand exceeds supply.To solve the above problems,technology of deep sea farming is widely used.Compared with offshore sea farming,deep sea farming means that the wave and current is stronger.So the net cage for fish farning will be easily destroied.In the meantime,the situation of wave and current is closely related to the grow of farming fish.As an important part of net cage,net is a kind of flexible object.Studies about net are rare.Due to what is said above, physical model tests and numerical simulation research were established to study effect of netting panels on wave propagation.In the study we tried to find mechanism of action between wave and net.Based on the rule,study of the mechanism of action between wave and net cage was also established.In order to simulate the net effects on wave propagation. Three-dimensional numerical wave tank are established, using porous media model to simulate the nets. With the three-dimensional numerical model, the study about the low of wave height through net panel was simulated, the result of the numerical simulation were compared with the result in physical experiment. The comparison showed that wave transmission coefficient in numerical simulation agreed well with the data in physical experiment.This content are composed of five parts. The first chapter gives a exhibition on the background of the subject and the aim of the study, the development tendency of the research is also refered. The second chapter is about the theory of the numerical model,including the governing equations,the tansformation between net and porous media model, the establish of the three-dimensional numerical wave tank and the method of its mesh dividing,theory of wave making and wave reduce. In the third chapter,we firstly take demonstration on the effectiveness of wave making and wave reduce. Then, we simulate the wave field around net panels with FLUENT, the numerical results are compared with data obtained in physical model tests. By comparision, we get to know the mechanism of interaction between net and wave. On this basis, we conclude a discipline about wave effects through net. In the forth chapter, we make the study about the difference on the wave propagation effect by the interaction of net panel with different underwater penetration. We also study the impact on wave form when we change the number of net panels. In the fifth chapter, we study the net cage effects on wave propagation on the basis of the conclusion we get from net panel tests. In addition, we monitored the change of wave form when we change the shape of net cage and the compactness of net.The last part is summary and discussion of all the study, there we take an exhibition of the study achievement.