Development of Numerical Model for Ratioanl end Effective Placement of Turbidity Fence

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Three numerical models, which include Model 1 based on LES method, Model 2 on FDS method, and Model 3 on SMAC method and MUSCL technique, are developed as a rational and effective method for placing turbidity fence to reduce diffusion of turbidity, which is induced by direct dumping of soil into coastal waters using a bottom-dump barge. Among these model, Model 1 and 3 can simulate three dimensional motion, diffusion and depositional process of the turbidity cloud, which falls and spreads under the action of its own buoyancy during the falling stage, subsequently the turbidity cloud impinges on the bottom boundary, and propagates horizontally along the bottom boundary during the spreading stage.The model performance is examined through two-and three dimensional experimental data. Considering stability, efficiency, accuracy, expandability and flexibility of the models, Model 3 is proposed as a practical model. Furthermore, Model 3 is applied practical situation in order to demonstrate ability of the model.In addition, in order to understand and clarify the fundamental of the phenomena, theoretical and experimental study is also conducted. A thermal theory for the falling stage, the transition depth from thermal phase to swarm phase in terms of-the dumping condition, the transition depth and speed from thermal phase in finite water depth, and others.