Analysis of open channel flow with various layered vegetation using CFD, considering different near-wall treatment methods

• Published in: International journal of numerical methods for heat & fluid flow 2024-03, Vol.34 (4), p.1780-1810
• Main Author: Şibil, Rahim
• Format: Article
• Language: English
• Subjects: Channel flow; Computational fluid dynamics; Creeks & streams; Eddy viscosity; Environmental conditions; Finite volume method; Floodplains; Flow characteristics; Flow velocity; Fluid dynamics; Fluid flow; Friction; Hydraulics; Hydrodynamics; Incompressible flow; Kinetic energy; Liquid-solid interfaces; Mathematical models; Numerical analysis; Numerical models; Numerical prediction; Open channel flow; Open channels; Plant cover; Plant growth; Reynolds number; Steady flow; Turbulence; Turbulent flow; Vegetation; Vortices
• ISSN: 0961-5539; 1758-6585; 0961-5539
• DOI: 10.1108/HFF-11-2023-0704

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.