Purpose

The purpose of this paper is to investigate the impact of near-wall treatment approaches, which are crucial parameters in predicting the flow characteristics of open channels, and the influence of different vegetation covers in different layers.

Design/methodology/approach

Ansys Fluent, a computational fluid dynamics software, was used to calculate the flow and turbulence characteristics using a three-dimensional, turbulent (k-e realizable), incompressible and steady-flow assumption, along with various near-wall treatment approaches (standard, scalable, non-equilibrium and enhanced) in the vegetated channel. The numerical study was validated concerning an experimental study conducted in the existing literature.

Findings

The numerical model successfully predicted experimental results with relative error rates below 10%. It was determined that nonequilibrium wall functions exhibited the highest predictive success in experiment Run 1, standard wall functions in experiment Run 2 and enhanced wall treatments in experiment Run 3. This study has found that plant growth significantly alters open channel flow. In the contact zones, the velocities and the eddy viscosity are low, while in the free zones they are high. On the other hand, the turbulence kinetic energy and turbulence eddy dissipation are maximum at the solid–liquid interface, while they are minimum at free zones.

Originality/value

This is the first study, to the best of the author’s knowledge, concerning the performance of different near-wall treatment approaches on the prediction of vegetation-covered open channel flow characteristics. And this study provides valuable insights to improve the hydraulic performance of open-channel systems.

中文翻译：

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使用 CFD 分析各种层状植被的明渠水流，考虑不同的近壁处理方法

目的

本文的目的是研究近壁处理方法的影响（这是预测明渠水流特征的关键参数）以及不同层不同植被覆盖的影响。

设计/方法论/途径

Ansys Fluent 是一种计算流体动力学软件，使用三维、湍流（可实现）、不可压缩和稳定流假设以及各种近壁处理方法（标准、可扩展、非平衡和增强）在植被通道中。该数值研究通过现有文献中进行的实验研究进行了验证。

发现

数值模型成功预测了实验结果，相对误差率低于10%。经确定，非平衡壁函数在实验运行 1 中表现出最高的预测成功率，在实验运行 2 中表现出标准壁函数，在实验运行 3 中表现出增强的壁函数。这项研究发现，植物生长显着改变了明渠流量。在接触区，速度和涡流粘度较低，而在自由区，速度和涡流粘度较高。另一方面，湍流动能和湍流涡耗散在固液界面处最大，而在自由区处最小。

原创性/价值

据作者所知，这是第一项关于不同近壁处理方法在预测植被覆盖的明渠水流特征方面的性能的研究。这项研究为提高明渠系统的水力性能提供了宝贵的见解。