Experimental Study of Force Balance and Interaction between Flow in the Main Channel and on the Floodplains in Skewed Compound Channel with Inclined Floodplains

مهندسی عمران فردوسی

Volume 34, Issue 2 - Serial Number 34, June 2021, Pages 87-102   

Document Type: Original Article

DOI: 10.22067/jfcei.2021.70767.1041

Authors

Mostafa Dolati Mahtaj; Bahram Rezaei^*

Department of Civil Engineering, Faculty of Engineering, Bu-Ali Sina University, Hamedan, Iran.

Abstract

In non-prismatic compound channels due to the mass and momentum exchange between the main channel and floodplains, the flow interaction between channel sub-sections is higher than prismatic compound channels. As a result, in this form of channels, the study of apparent shear forces create at the vertical interface between the main channel and floodplains are much more complex. In the present research, the velocity and boundary shear stress distributions were measured at different sections along the skew part of the flume. Also using the experimental data and the momentum equations the flow interaction between the main channel and floodplains have been investigated. Measurements have been performed for two skew angles of 11.31 and 3.81 degrees and three relative depths of 0.2, 0.3 and 0.4. Investigations indicate that the flow interaction between the main channel and the converging floodplain is generally greater than the flow interaction between the main channel and the diverging floodplain. Also, the side slope of the floodplains, has increased the amount of apparent shear force at the interface between the main channel and floodplains.

Keywords

Flow interaction; Force balance; Skewed compound channel; Inclined floodplains; Apparent shear force

Supplementary Files

6- rezaie.pdf

References

1. Sellin, R. H. J., "A Laboratory Investigation into the Interaction between the Flow in the Channel of a River and that Over its Flood Plain", La Houille Blanche, 7, pp. 793-802, (1964).
2. Tominaga, A., and Nezu, I., "Turbulent Structure in Compound Open-channel Flows", Journal of Hydraulic Engineering, ASCE, Vol. 117, No. 1, pp. 21-41, (1991).
3. Chlebek, J., "Modelling of Simple Prismatic Channels with Varying Roughness Using the SKM and a Study of Flows in Smooth Non-Prismatic Channels with Skewed Floodplains", Birmingham University, (2009).
4. James, M., and Brown, B. J., "Geometric Parameters that Influence Floodplain Flow, Waterways Experiment Section", Hydraulics Laboratory, Department of Defense, US Army Corps of Engineering, Report H-77-1, Vicksburg, Mississippi, (1977).
5. Jasem, H. K., "Flow in Two-Stage Channels with the Main Channel Skewed to the Flood Plain Direction", University of Glasgow, (1990).
6. Ervine, D. A., and Jasem, H. R., "Observation on Flows in Skewed Compound Channels", Proceedings of the Institution of Civil Engineers-Water, Maritime and Energy, ICE, Vol. 112, No. 3, pp. 249-259, (1995).
7. Dolati Mahtaj, M., "Experimental Study of Flow in Skewed Compound Channel with Inclined Floodplains", Bu-Ali Sina University, (2021). (In Persian)
8. Elliott, S. C. A., and Sellin, R. H. J., "SERC Flood Channel Facility: Skewed Flow Experiments", Journal of Hydraulic Research, IAHR, Vol. 28, No. 2, pp. 197-214, (1990).
9. Sellin, R. H. J., "Hydraulic Performance of a Skewed Two-Stage Flood Channel", Journal of Hydraulic Research, IAHR, Vol. 33, No. 1, pp. 43-64, (1995).
10. Seif, M. M., and Rezaei, B., "Numerical Study on the Effects of the Floodplains Angles on Interaction between the Main Channel and Floodplains in Skewed Compound Channels", journal of Ferdowsi Civil Engineering, 32, No. 1, pp. 151-164, (2019). (In Persian)
11. Elliott, S. C. A., "An Investigation into Skew Channel Flow", University of Bristol, (1990).
12. Chlebek, J., Bousmar, D., Knight, D. W., and Sterling, M., "A Comparison of Overbank Flow Conditions in Skewed and Converging/ Diverging Channels", Proceedings of the River Flow 2010, Braunschweig, Germany, Vol. 1, pp. 503-511, (2010).
13. Bousmar, D., Jacqmin, T., Wyseur, S., and Van Emelen, S., "Flow in Skewed Compound Channels with Rough Floodplains", Proceedings of the River Flow 2012, San Jose, Costa Rica, Vol. 1, pp. 217-224, (2012).
14. Rezaei, B., and Knight, D. W., "Overbank Flow in Compound Channels with Non-Prismatic Floodplains", Journal of Hydraulic Engineering, ASCE, Vol. 137, No. 8, pp. 815-824, (2011).
15. Rezaei, B., "Overbank Flow in Compound Channels with Prismatic and Non-Prismatic Floodplains", Birmingham University, (2006).