Flow Pattern around the Vertical Spur Dikes in A 90-Degree Mild Bend with Computational Fluid Dynamics

In order to protect the bank and prevent their erosion spur dike is used. Importance of these structures in the bend is more, because of secondary flows and consequently bank erosion. In this paper the flow pattern around series of vertical spure dikes in the 90° bend is investigated by a 3D RANS solver. In order to simulate the complex behavior of free surface and turbulent flow the volume of fluid method and realizable k-ɛ closure have been used, respectively. Two lengths spure dike (equal to 15 and 25 percent of width), two spacing (3 and 5 three times the length) and two depths (3 and 5cm) in constant discharge 25 lit/s in the mild bend flume with width 0.7m and depth 0.12 m has been examined. Comparison among the results with experimental data shows good agreement among them. Also, the results illustrate spure dike deviations maximum velocity to the inner bank in entrance of bend and then deviations to the middle flume. Increasing the length of the spure dikes increases the velocity but it has no effect on the location of the maximum velocity as in all arrangement occurrence in 71 to 81 degree of bend. In the case of shear stress, the maximum value is in the range of 71 to 81˚.