Study On The Flow Characteristics Around Double Spur Dikes Using Flume Experiment And Numerical Simulation

Spur dike is a hydraulic structure frequently used in river regulation projects, coastal protection projects and flood control projects. Studies on the flow structure around the spur dike are of great value of hydraulics research, and also provide instructional advice for the identifying its size, optimization of the spur dike head patterns and distance.In this paper, we make a brief review and comment for research status on the flow structure around the spur dike. Combined with result of previous studies, using physical model test and numerical simulation method to theoretically study the flow characteristics around the double spur dikes deeply.In terms of physical model experiment, experiment with different flow rate and water level tested flow characteristics in the flume. The main studies include the variation of the flow field distribution and the water level along flowing, and the influence of different flow rate and different water level on flow characteristics near the double spur dikes. Experimental results show that,(1)Double spur dikes have played a good role in adjusting flow structure near the spur dike. The flow direction of the water has the apparent deflection in front of the jetty head of spur dike. There are different size of the vortices near the spur dike, and forming a recirculation zone between the double spur dikes.(2)There is a backwater phenomenon in the upstream of the first spur dike, the water level rising and the velocity decreasing, and there is a drop phenomenon after passing the dam with the water level decreasing obviously, until the upstream of the second spur dike. The water level slowly recovers away from a distance at the downstream of the second spur dike.(3)The high flow velocity zone of the first spur dike is located jetty head. The high flow velocity zone distribution of the second spur dike is bias towards in the middle of main channel. The combined effect of them makes flow velocity redistribute.(4)The first spur dike, with the increase of water discharge, the high velocity zone of the jetty head region moves to spur dike upstream, The second spur dike, with the increase of water discharge, and the flow pattern of near spur dike will gradually occur disorder.(5)The first spur dike, with the increase of water level, the high velocity zone of the jetty head region moves to spur dike downstream. The second spur dike, with the increase of the water level, the flow pattern of near spur dike will gradually appear the phenomenon of smooth and steady.In numerical simulation, using MIKE3 to simulate the distribution of flow field and variation of water level. Verify the simulated results with the physical experiment results. Fitting result is good. Proved that the established MIKE3 numerical model for analyzing the flow characteristics around the double spur dikes is feasible And on this basis, this model was applied to simulate the three-dimensional flow characteristics near the double spur dikes under different conditions respectively. Simulation results show that,(1)There are a wide range of high velocity zone near the middle of main channel. The range of high velocity zone in the x direction in the vertical at the near-bottom to the near-surface increases gradually.(2)The flow velocity in the y direction is less than the flow velocity in the x direction. There are relatively large velocity zones near the jetty head. The range of these velocity zones distribution in the near-surface, middle and near-bottom layer is basically the same.(3)The flow velocity is smaller in z direction. There is a small range of the relatively large velocity zone near the jetty head of the first spur dike, and it is distributed in the near-surface, middle and near-bottom. But relatively large velocity zone near the jetty head of the second spur dike is distributed in the near-surface, middle layer.