Abstract
Local scour is a common threat to structures such as bridge piers, abutments, and dikes that are constructed on natural rivers. To reduce the risk of foundation failure, the understanding of local scour phenomenon around hydraulic structures is important. The well-predicted scour depth can be used as a reference for structural foundation design and river management. Numerical simulation is relatively efficient at studying these issues. Currently, two-dimensional (2D) mobile-bed models are widely used for river engineering. However, a common 2D model is inadequate for solving the three-dimensional (3D) flow field and local scour phenomenon because of the depth-averaged hypothesis. This causes the predicted scour depth to often be underestimated. In this study, a repose angle formula and bed geometry adjustment mechanism are integrated into a 2D mobile-bed model to improve the numerical simulation of local scour holes around structures. Comparison of the calculated and measured bed variation data reveals that a numerical model involving the improvement technique can predict the geometry of a local scour hole around spur dikes with reasonable accuracy and reliability.
Highlights
Most of the empirical formulas have limitations to calculate the scouring depth or hole shape changing over time
An empirical formula for calculating the sediment repose angle [16] and the bed geometry adjustment mechanism are integrated into the CCHE2D numerical model to improve the simulation of the local scour hole around a hydraulic structure
In the research of hydraulics and river dynamics, the understanding of the local scour phenomenon by the streams or the flood around hydraulic structures is important to reduce the risk of foundation structure failure
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The sediment entrainment and transport around the scour hole are related to the turbulence fluctuation, characteristics of sediment, bed-load with the gravity projection, and the bed geometry of a slope that have crucial effects on incipient sediment motion. This angle is an essential parameter for understanding the microbehavior of granular material and relating this behavior to the material’s macrobehavior Both an empirical formula and a numerical model can be used to evaluate the equilibrium scour depth around a hydraulic structure. An empirical formula for calculating the sediment repose angle [16] and the bed geometry adjustment mechanism are integrated into the CCHE2D numerical model to improve the simulation of the local scour hole around a hydraulic structure. By improving the 2D numerical simulations on local scour hole around spur dike, it will provide practical application value in terms of model efficiency and speed
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