Lateral intakes are hydraulic structures used for domestic, agricultural and industrial water conveyance, characterized by a very complex three-dimensional morphodynamic behavior: since streamlines near the lateral intake are deflected, some vortices form, pressure gradient, shear and centrifugal forces at the intake generate flow separation and a secondary movement, responsible for local scour and sediment deposition. On the other side, the modeling of flows, besides the sediment transport, in curved channels implies some more complications in comparison with straight channels. In this research, this complex process has been investigated experimentally and numerically, with the mechanism of sediment transport, bed topography evolution, flow pattern and their interactions. Experiments were performed in the Laboratory of Tarbiat Modares University, Iran, where a U-shaped channel with a lateral intake was installed and dry sediment was injected at constant rate into a steady flow. Due to the spiral flow, the bed topography changes significantly and the bed forms in turn affect the sediment entering the intake. Different from the previous works on this topic which were mainly based on laboratory experiments, here, Computational Fluid Dynamics (CFD) numerical simulations with FLUENT software were also performed, specifically with the two-phase Eulerian Model (EM) and Discrete Phase Model (DPM), at the aim of evaluating their performance in reproducing the observed physical processes. This software is used for a large variety of CFD problems, but not much for simulating sediment transport phenomena and bed topography evolution. The comparison of the results obtained through the two models against the laboratory experimental data proved a good performance of both the models in reproducing the main features of the flow, for example, the longitudinal and vertical streamlines and the mechanism of particles movement. However, the EM reveals a better performance than DPM in the prediction of the secondary flows and, consequently, of the bed topography evolution, whereas the DPM well depicts the particles pattern, predicts the location of trapped particles and determines the percentage of sediment entering the intake.The numerical models so calibrated and validated were applied to other cases with different positions of the intake in the bend. The results show that mechanism of sediment entrance into the intake varies in different position. If the intake is installed in the second half of the bend, the sediment accumulates along the inner bank of the bend and enters the intake from downstream edge of intake; on the other side, if it is placed in the first half of the bend, the sediment accumulates along both the inner and the outer bends and, therefore, more sediment enters the intake. Also the results of the simulations performed with the DPM model for different positions of the lateral intake show that for all discharge ratios, the position of 120∘is the one which guarantees the minimum ratio of sediment diverted to the intake (Gr).

中文翻译：

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横向进水的 180° 弯曲通道中的沉积物输送和床演化：使用欧拉和离散相模型的数值模拟

横向进水口是用于生活、农业和工业输水的水力结构，其特点是非常复杂的三维形态动力学行为：由于横向进水口附近的流线发生偏转，因此会形成一些涡流，在进水口处产生压力梯度、剪切力和离心力流动分离和二次运动，负责局部冲刷和沉积物沉积。另一方面，与直线通道相比，弯曲通道中的流动建模除了泥沙输送外，还意味着一些更复杂的问题。在这项研究中，这个复杂的过程已经通过实验和数值方法进行了研究，包括泥沙输送机制、河床地形演化、流动模式及其相互作用。实验在 Tarbiat Modares 大学的实验室进行，伊朗，在那里安装了一个带有横向进水口的 U 形通道，并以恒定的速度将干燥的沉积物注入稳定的水流中。由于螺旋流，河床地形发生显着变化，河床形态反过来影响进入进水口的沉积物。与以前主要基于实验室实验的该主题的工作不同，这里还使用 FLUENT 软件进行了计算流体动力学 (CFD) 数值模拟，特别是两相欧拉模型 (EM) 和离散相模型 (DPM) )，目的是评估它们在再现观察到的物理过程中的表现。该软件用于解决各种 CFD 问题，但在模拟泥沙输送现象和河床地形演变方面并不多。通过两种模型获得的结果与实验室实验数据的比较证明，两种模型在再现流动的主要特征方面表现良好，例如纵向和垂直流线以及粒子运动机制。然而，EM 在预测二次流和因此的床形演变方面显示出比 DPM 更好的性能，而 DPM 很好地描绘了颗粒模式，预测了捕获颗粒的位置并确定了进入泥沙的百分比。进气口。如此校准和验证的数值模型被应用于弯道中进气口位置不同的其他情况。结果表明，不同位置的泥沙进入取水口的机理不同。如果进水口安装在弯道后半部，泥沙沿弯道内岸堆积，从进水口下游边缘进入进水口；另一方面，如果将其放置在弯道的前半部分，则泥沙会沿内弯和外弯堆积，因此会有更多的泥沙进入进水口。此外，使用 DPM 模型对横向进气口的不同位置进行的模拟结果表明，对于所有排放比，120 的位置∘是保证转移到进水口 (Gr) 的最低比例的沉积物。