Numerical study of the effect of changing the geometric parameters of intake and the arrangement of submerged vanes on the anti-sediment coefficient

Document Type : Research Article


Department of Civil Engineering, Buin Zahra Branch, Islamic Azad University, Buin Zahra, Iran


Lateral intakes are used to divert water from the main river. One of the crucial points in the design of intakes is to provide conditions that supply maximum intake with minimum sediment. In addition to dewatering from the outer bank of the river, it is recommended to build a sill at the inlet of the intake and also to use submerged vanes to remove the bed load to the intake. Submerged vanes are plate-shaped structures that are installed in the bed of rivers and canals at an angle to the flow. The primary function of submerged vanes is to create a secondary flow, so they play a significant role in controlling inlet sediment to the lateral intake. There have been many studies on the use of submerged vanes in front of lateral intakes. In all previous laboratory and numerical studies, the geometric parameters of the intake have been fixed, and laboratory-scale studies have been performed. In the present study, simulations have been performed in geometries close to natural conditions. Also, the intake is installed in different positions and angles, and by changing the width and height of the sill, the submerged vanes with two different arrangements are placed in front of the intake. The effect of vanes and change of intake parameters on the amount of sediment entering the intake and the anti-sediment coefficient have been investigated.
In the case of modeling in geometries close to natural conditions, the use of numerical models is necessary. The numerical model is used as a virtual laboratory, but in natural dimensions. Therefore, in the present study, numerical modeling has been used. The numerical model used (SSIIM2) solves the flow field by solving the Navier-Stokes three-dimensional equations using the finite volume method. To validate the numerical model, the junction of Kaskaskia River and Cooper River was simulated, and the bed changes predicted in the numerical model were compared with Rhoads (1996) field results. Comparing the results showed that the pattern of sedimentation and scouring in the numerical model is similar to field data. The numerical model has well predicted the location of scouring and sedimentation. In the present study, the intake has been installed in a 50-degree bend channel whose hydraulic dimensions and conditions are close to a part of Karkheh River. 27 numerical studies have been performed to investigate the effect of using submerged vanes on the value of the anti-sediment coefficient. Studies have been performed in three groups of 9. The first group had no submerged vanes (No vane), the second group had two rows of submerged vanes installed upstream of the intake (Layout1), and the third group had four rows of submerged vanes placed both upstream and in front of the intake (Layout2). In each category, the geometric parameters affecting the performance of the lateral intake that are dimensionless compared to the main channel parameters are the ratio of the intake width to the width of the main channel (Bi/Bm), the position of the catchment in the arc (θci/θc), intake angle (αi) And the ratio of sill height to flow depth (hs/hm). Each of these parameters is considered at three levels of change, as table1. In each of the 27 cases studied, the flow field is first dissolved, and after the convergence of the flow field, suspended sediment is injected from upstream on the rigid bed.
Results and Discussion
The radial velocity profile (ur) in the bend can be a measure of secondary flow strength. When the surface flow and the bed flow are opposite in both directions, the velocity profile is α-shaped, so a strong secondary flow is generated. If the velocity profile is β-shaped, the flow direction is in the same direction at the surface and the bed, and no secondary flow occurs. The closer the radial velocity profile is to the α-shape, the greater the secondary flow strength. The presence of the intake in the bend leads to the weakening of the secondary flow in the area affected by the intake and even the radial velocity is β-shaped, which is one of the factors in transferring sediment to the intake. The presence of submerged vanes have led to a change in the type of velocity profile from β to α. In general, the use of Layout1 has resulted in an average reduction of 15% in the amount of sediment entering the intake. In contrast, the use of submerged vanes upstream and in front of the intake, Layout2, has reduced the average amount of sediment by 46% to the intake. In studies (Barkdoll et al., 1999) that investigated the effect of using submerged vanes in controlling inlet sediment to the lateral intake on a straight channel with alluvial bed, three rows of submerged vanes were used upstream and in front of the intake. The results of theirs studies showed that for the discharge flow of 0.16 (Compared to discharge flow 0.25 of the present study), the submerged vanes led to a 35% reduction in the sediment ratio to the intake. For the flow ratio of 0.24, the submerged vanes caused a 50% reduction in the sediment ratio to the intake.
In the case where Bi/Bm>=35%, Layout1 did not affect the value of the anti-sediment coefficient. That is, if the intake’s width is large, it is necessary to install submerged vanes in front of the intake to be able to affect the amount of sediment entering the intake. In general, by changing the levels of the parameters θci/θc, αi, and hs/hm, Layout1 has led to an average increase of 59% in the anti-sediment coefficient. Layout2, on the other hand, has resulted in an average 148% increase in the anti-sediment coefficient compared to the case where no submerged vanes are used in the bend.
Keywords: Lateral intake, bend, numerical simulation, SSIIM.


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  • Receive Date: 10 October 2020
  • Revise Date: 14 November 2020
  • Accept Date: 15 November 2020
  • First Publish Date: 15 November 2020