Development of a CFD model and procedure for flows through in-stream structures

Abstract

Large wood (LW) has been widely used in river restoration projects due to its ecological benefit. 3D modeling has rarely been conducted. In this study, a 3D modeling procedure is proposed and a new 3D model is developed. The model incorporates advanced CFD techniques and is easy to apply. An engineered log jam (ELJ) is constructed and an experiment is conducted. The data are used to demonstrate the procedure and validate the CFD model. A comparison of the predicted and measured velocity shows that agreement is good with the Nash-Sutcliffe coefficient about 0.4 and index of agreement about 0.85. The model is further applied to a curved channel with ELJ on the outer bank, demonstrating the use of the 3D model to guide the proper representation of ELJs in a 2D model. The 3D model may be used to reveal complex flow patterns generated by LW for ecological benefit analysis.

KEYWORDS:

• 3D CFD model
• URANS
• unstructured mesh
• engineered log jam
• large wood

Acknowledgements

It is acknowledged that Prof. Xiaofeng Liu, the Department of Civil and Environmental Engineering, Penn State University, University Park, PA, USA, provided valuable contributions in supervising his PhD student Y. Xu in developing the windows-based SHM software and generating the 3D mesh.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Bureau of Reclamation Science and Technology Office [1734].

Notes on contributors

Yong G. Lai

Yong Lai is a specialist hydraulic engineer at the Technical Service Center, U.S. Bureau of Reclamation, Denver, Colorado. Dr Lai obtained his PhD in 1990 from Arizona State University and has since been involved in a wide range of research, development and engineering projects. His professional career includes working for a consulting company, a research institute, the University of Iowa, and now the federal government. Dr Lai has published more than 60 scientific journal papers and numerous conference papers in diverse engineering areas. He is the lead author of the 2D flow and sediment transport model SRH-2D and the 3D CFD model U2RANS. Dr Lai currently serves as an associate editor of the ASCE Journal of Hydraulic Engineering and a member of the Scientific Advisory Board for several conferences. He regularly provides short courses on hydraulic and sediment modeling.