Simulation of Migration Processes in Alluvial Channel Using 2-D Depth Averaged Model
The special features of the 2-D explicit finite analytic depth-averaged mobile bed numerical model derived on non-orthogonal curvilinear coordinate system include: (1) the development of a generalized body-fitted coordinate system to describe the irregular boundary of natural river; (2) the adoption of the finite-analytic method, which is different from the common finite-difference or finite-element method, and is originally proposed for solving the fluid-mechanics problems with great success; (3) non-uniform sediment transport in form of suspended and bed load, with the consideration of exchange mechanic between them. In order to expand the model applicability, the study established lateral bank migration mechanics in the previous framework. The established mechanics would clarify the later mobile migration behavior. The model had developed bank erosion mechanism of non-cohesive sediment and rotational and planar failure mechanisms of cohesive sediment. Through the simulation of testing cases, it had shown that the upstream water discharge played an important role in the bank erosion mechanism of non-cohesive sediment, while the soil critical shear stress had most effect in the rotational and planar failure mechanisms of cohesive sediment. In the simulation of practical cases, it had suffered enormous challenge of alternative dry and wet bed problem. At the present time, the model could simulate the cases of less complex channel morphology. It is suggested to pay more attentions to this problem to enhance the model practicability.
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