Numerical Study of the Effects of Non-Prismatic Floodplain Divergence Angle on Flow Velocity in the Cross Section of Compound Channels

Shokri, Morteza; Mehdipour, Reza

doi:10.22034/jewe.2021.250562.1434

Document Type : Research Paper

Authors

Morteza Shokri ¹
Reza Mehdipour ²

¹ Assist. Professor, Department of Civil Engineering, Kabodarahang Engineering Faculty, Bu-Ali Sina University, Hamedan, Iran

² M.E. Student, Department of Civil Engineering, Faculty of Engineering, Bu Ali Sina University, Hamadan, Iran

https://doi.org/10.22034/jewe.2021.250562.1434

Abstract

The formation of the secondary flows is caused by the non-prismatic nature of the main channel and floodplains in the compound channel and the intense interaction of the low-velocity flow of the floodplains in passing over the high-velocity flow of the main channel. So far, comprehensive studies on changing the divergence angle of floodplains have not been done as a numerical and physical model, and due to the effectiveness of this parameter, its study is necessary. In the present study, using the three-dimensional Ansys-Fluent model, simulation was performed based on the standard k-ε turbulence model and VOF method for the hydraulic flow in compound channel with divergent floods for five divergence angles of 3, 6, 9, 12 and 15° and in three sections of 2, 8 and 14 m. The boundary conditions used in this research were the input limit of the mass flow rate, the output boundary as a pressure outlet, the solid boundaries as a non-slip wall without roughness and the upper boundary of the channel as a non-slip wall without roughness. The results of accurately predicting the average depth velocity in the section Z = 14 m of the channel showed that in all sections of the channel, the modeling results were within the allowable error range defined for numerical models, indicating the appropriate matching of laboratory and simulation results. The results showed that the maximum velocity in the channel occurs with a divergence angle of 3° and the higher the divergence angle, the lower the velocity. Moreover, the maximum shear stress in the channel is with a divergence angle of 3° and the minimum shear stress is in the divergence angle is 15°. The lower the water angle, the higher the divergence angle, and the higher the divergence angle, the lower the water height.

Keywords

Main Subjects

Hydraulic and river engineering

References

Amini A., and Asadi Parto, A. (2017). 3D numerical simulation of flow field around twin piles. J. Hydrol., DOI 10.1007/s11600-017-0094-x.

Bakker, B., Vermaas, H. and Choudri, A. M. (1989). Regime theories updated or outdated. Delft Hydraul., 416, 1-7.

Bousmar, D. (2002). Flow modelling in compound channels: momentum transfer between main channel and prismatic or non-prismatic floodplains. Thesis Presented for the degree of Doctor in Applied Sciences, Leuven Catholic University of Applied Sciences, Department of Civil and Environmental Engineering, 306.

Chlebek, J. (2009). Modelling of simple prismatic channels with varying roughness using the SKM and a study of flows in smooth non-prismatic channels with skewed floodplains (Doctoral dissertation, University of Birmingham).

Das, B. and Khatua, K. (2018). Water surface profile computation for compound channel having diverging floodplains. ISH J. Hydraul. Eng., 23(2), 336-349.

Das, B. S., Devi, K. and Khatua, K. K. (2019). Prediction of discharge in converging and diverging compound channel by gene expression programming. ISH J. Hydraul. Eng., 1-11. Doi: 10.1080/09715010.2018.1558116

Devi, K., Khatua, K. K. and Das B. S. (2016). Apparent shear in an asymmetric compound channel. Iowa City, USA, River Flow, 48, 48-56.

Fazli, M., Esfaniari, S. and Rezaei, B. (2013). Comparison of the results of numerical flow simulation in prismatic compound channels with different turbulence models. 9^th International Congress of Civil Engineering, Isfahan University of Technology, 9 [In Persian].

Heidarzade, M. (2015). Applied computational fluid dynamics with ansys fluent, Kian University Press, Tehran, Congress Ranking, QA911/9D9H, 260. [In Persian].

Khatua, K. and Patra, K. C. (2007). Boundary shear distribution in meandering compound channel flow. Proceedings of the 5^th Australian Stream Management Conference, Australian Rivers: Making a Difference. Charles Sturt University, Thurgoona, New South Wales, 193-198.

Kishnajit Kumar, K. and Kanhu Charan, P. (2007). Boundary shear stress distribution in meandring compound channel flow. Proceedings of the 5^th Australian Stream Management Conference. Australian rivers: making a difference. Charles Sturt University, Thurgoona, New South Wales. 193-198.

Mohanty, P. K., Khatua, K. and Patra, K. C. (2011). Investigation on shear layer in compound channels. National Conference Hydraulic and Water Resources Hydro, During December 29-30, SVNIT Surat, Surat.

Mohanta, A., Patra, K. C. and Khatua, K. K. (2014). CFD simulation and two-phase modeling of a non-prismatic converging compound channel. National Conference on Advances in Engineering and Technology, At: Maharishi Markandeshwar University, Mullana - Ambala, 17-23.

Naik, B., Khatua, K. K., Wright, N. G. and Sleigh, A. (2017). Stage dischargw prediction for converging compound channels with narrow floodplains. J. Irrig. Drain. Eng., 143(8), 28. Doi: 10.1061/(ASCE)IR.1943-4774.0001184

Najafian, S. (2016). Flow Simulation in non-prismatic compound sections using flow 3D model. Master Thesis in Water Engineering, Branch of Hydraulic Structures, University of Lorestan, Faculty of Agriculture, 123 [In Persian].

Naghibi Neishapoori, N. and Sagharvani, M. (2013). Investigation of sediment transfer in sandy rivers. Master Thesis, Shahroud University of Technology, Faculty of Civil Engineering and Architecture, Department of Civil Engineering [In Persian].

Sekhar Reddy, Y. (2016). Application of K-e model to compound channels having diverging floodplains and analysis of flow parameters using ansys (fluent). Department of Civil Engineering National Institue of Technology Rourkel: Dissertation submitted in partial fulfillment of the requirements of the degree of bachelor of Technology in Civil Engineering, 56.

Sajjadi, S. H. and Sarkardeh, H. (2018). Accuracy of numerical simulation in asymmetric compound channels. Int. J. Civil Eng., 16(2), 155-167.

Younesi, H. A., Omid, M. H. and Ayyoubzadeh, S. A. (2013). The hydraulics of flow in non-prismatic compound channels. J. Civil Eng. Urban, 3(6), 342-356.

Younesi, H., Omid, M. H. and Ayoub Zade, S. (2015). Effect of flood roughness on flow hydraulics in compound sections with non-prismatic flood. Iran. Water Res. J., 6(2), 93-100 [In Persian].

Younsei, H. A., (2013). Study of bed load transfer in the main channel of a compound channel with non-prismatic floodplain. PhD Thesis, University of Tehran, Irrigation and Development Course [In Persian].

Yousefi, R. (2018). Study of velocity and boundary shear stress distributions in compound channels with converging floodplains using numerical modeling (CFD) and artificial neural. Master Thesis, Faculty of Engineering, Bu Ali Sina University, Hamedan[In Persian].

Zahiri, A. (2010). Simulation of gradual variable flow in compound sections. J. Soil Water Conserv. Res., 17(4), 181-190 [In Persian].

Environment and Water Engineering

Numerical Study of the Effects of Non-Prismatic Floodplain Divergence Angle on Flow Velocity in the Cross Section of Compound Channels

References

References

Volume 7, Issue 3
November 2021
Pages 454-464

Numerical Study of the Effects of Non-Prismatic Floodplain Divergence Angle on Flow Velocity in the Cross Section of Compound Channels

References

References

Volume 7, Issue 3November 2021Pages 454-464

Volume 7, Issue 3
November 2021
Pages 454-464