Author(s): A. Savarian; N. Talebbeydokhti; A. H. Nikseresht
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Keywords: No Keywords
Abstract: The bed evolution is a complex phenomenon resulting from the interaction of the three-dimensional turbulent flow field in the bend and the mobile river bed. The bed evolution prediction methods developed in the laboratories and the sediment transport equations based on laboratory data did not always produce reasonable results for field conditions. Recent researches indicate that laboratory investigations often oversimplify or ignore many of the complexities of the flow fields in river bends and it is not practical for a physical model of bed evolution in river bend to satisfy all these similarities. However, unlike a physical model, the CFD model employs the actual dimensions and operating conditions to calculate turbulent flow field and sediment transport. In this research, the flow and river bed evolution in alluvial channel bends are numerically simulated using Eulerian two-phase model that implements Euler-Euler coupled governing equations for fluid and solid phases and a modified k-ε turbulence closure for the fluid phase. Both flow-particle and particle-particle interactions are considered in the model. During the simulations, the interface between sand and water is specified using a threshold volume fraction of sand and the evolution of the bed form is studied in detail. The predictions of bed form evolution are in good agreement with previous laboratory measurements.
Year: 2009