A 2-D Vertical Finite-Element Model for Sediment Transport Due to Tidal Flow

Author(s):  
Shi Sen Li ◽  
Tao Liu ◽  
Guojie Li ◽  
Jie Gao

An estuarine two-dimensional vertical finite-element model of suspended sediment transport has been established by the sediment conservation equation. The primary objective of the present paper is to develop and verify a 2DV estuarine tidal flow and sediment transport model derived by the moving grid FEM. To this end, finite-element method has been used. An arbitrarily shaped quadrilateral element has been selected. This model has been compared with analytical solution. The tidal flow model was developed by Li and Shi. This represents a step towards developing a general 2DV estuarine model.

Author(s):  
Dwinanti Rika Marthanty ◽  
Herr Soeryantono ◽  
Erick CARLIER ◽  
Dwita Sutjinigsih

There have been attempts to simulate meander dynamics (Langbein and Leopold 1966, Oodgard 1989, Campoerale et. al 2007, da Silva and El-Tahawy 2008, Duan and Julien 2010, Blanckaert and de Vriend 2010, Esfahani and Keshavarzi 2011). Meandering geometry is complex phenomena (Chanson 2004, Wu 2008), this would include the dynamics of flow properties and of morphology. Simulating meander flow dynamics is mostly popular using either Finite Element Method (FEM) or Finite Volume Method (FVM) where are based on Eulerian description, and based on stationer grid-based methods (Wormleaton and Ewunetu 2006, Wu 2008, Duan and Julien 2010, Gomez-Gesteira et. al 2010). As such this model is lack of capability in simulating the dynamics of meander morphology; much effort is put through to overcome this issue with such as Smoothed Particle Hydrodynamics (SPH), Boundary Element Methods, Arbitrary Lagrangian Eulerian, etc. This paper has two objectives; to identify meander flow characteristics and sediment transport distribution patterns, and to simulate meander flow characteristics and sediment transport distribution patterns using FEM. This study has identified that the key of dynamics of flow characteristics are helical flow and coherent structures, and the key of dynamics of transport characteristics are erosion-deposition zone patterns. The finite element model using in this study, RMA has shown its capability to simulate the meander key characteristics above, for small deflection angles (30°) location of maximum erosion-deposition zones near the crossover of the sinuosity, for intermediate deflection angles (70°) location of maximum erosion-deposition zones between the crossover and apex of the sinuosity, and for large deflection angles (110°) location of maximum erosion-deposition zones near the apex of the sinuosity, these are agreed with experiments of Odgaard 1989, da Silva 2006, da Silva et. al 2006, and Esfahani and Keshavarzi (2012). These results can be used as a reference to develop a method to model meander morpho-dynamics.


Fluids ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 18 ◽  
Author(s):  
Yong Lai ◽  
Kuowei Wu

Three-dimensional (3D) hydrostatic-pressure-assumption numerical models are widely used for environmental flows with free surfaces and phase interfaces. In this study, a new flow and sediment transport model is developed, aiming to be general and more flexible than existing models. A general set of governing equations are used for the flow and suspended sediment transport, an improved solution algorithm is proposed, and a new mesh type is developed based on the unstructured polygonal mesh in the horizontal plane and a terrain-following sigma mesh in the vertical direction. The new flow model is verified first with the experimental cases, to ensure the validity of flow and free surface predictions. The model is then validated with cases having the suspended sediment transport. In particular, turbidity current flows are simulated to examine how the model predicts the interface between the fluid and sediments. The predicted results agree well with the available experimental data for all test cases. The model is generally applicable to all open-channel flows, such as rivers and reservoirs, with both flow and suspended sediment transport issues.


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