Two-Dimensional Depth-Averaged Flow Modeling with an Unstructured Hybrid Mesh |
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Authors: | Yong G Lai |
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Affiliation: | Hydraulic Engineer, Sedimentation and River Hydraulics Group, Technical Service Center, Bureau of Reclamation, Denver, CO 80225. E-mail: ylai@usbr.gov
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Abstract: | An unstructured hybrid mesh numerical method is developed to simulate open channel flows. The method is applicable to arbitrarily shaped mesh cells and offers a framework to unify many mesh topologies into a single formulation. A finite-volume discretization is applied to the two-dimensional depth-averaged equations such that mass conservation is satisfied both locally and globally. An automatic wetting-drying procedure is incorporated in conjunction with a segregated solution procedure that chooses the water surface elevation as the main variable. The method is applicable to both steady and unsteady flows and covers the entire flow range: subcritical, transcritical, and supercritical. The proposed numerical method is well suited to natural river flows with a combination of main channels, side channels, bars, floodplains, and in-stream structures. Technical details of the method are presented, verification studies are performed using a number of simple flows, and a practical natural river is modeled to illustrate issues of calibration and validation. |
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Keywords: | Hybrid methods Mesh generation Two-dimensional models Open channel flow |
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