Experimental and numerical investigation the effect of pier position on local scouring around bridge pier at a 90° convergent bend

Document Type: Research Paper


1 Faculty member of Civil Engineering, Islamshahr Branch, Islamic azad university, Iran

2 Department of Civil Engineering, Eqhlid Branch, Islamic Azad University, Eqhlid, Iran

3 Department of Water Engineering, Isfahan University of Technology, Isfahan, Iran



Natural rivers have several bends along the path that are not generally uniform and some are convergent. Installing the bridge piers in river convergent bends may result in complicated flow and erosion patterns around the bridge piers. Most of previous studies on the flow and the scour pattern around piers were carried out in straight channels and fixed-width bends. Studying the local scouring around pier located at a converging bend, experimentally and numerically, has brought novelty to this paper. In this research, a physical hydraulic model with a 90° convergent bend and central radius of 170 cm was built. A cylindrical pier with a diameter of 60 mm was installed in positions of 0, 30, 45, 60, and 75 degrees and local scour were studied under clear-water conditions. The SSIIM-2 numerical model was also used to simulate the scour pattern and the results were compared with experimental results. The results showed that, increasing the convergence and changing the pier position in a bend leads to an increment in the continuity between the flow lines and secondary currents, respectively, so that the maximum depth and volume of the scour hole occurred in the second half of the bend at an angle of 75 degrees. The comparison between experimental and numerical data shows that SSIIM-2 model can efficiently simulate the scour pattern in a 90° convergent bend. Furthermore, in all cases by increasing the Froude number, maximum depth and volume of the scour hole were increased.


  1. Vijayasree BA, Eldho TI, Mazumder BS, Ahmad N, (2019). Influence of bridge pier shape on flow field and scour geometry. International Journal of River Basin Management, 17(1):109-129.
  2. Rozovskii I.L., Flow of Water in Bend of Open Channels, Academy of Sciences of the Ukrainian SSR, Kiev, 1957.
  3. Breusers H.N.C., Raudkivi A.J., Scouring. Hydraulic structures design manual, Balkema, Rotterdam, 1991.
  4. Vaghefi M, Ghodsian M, Salimi S, (2016). The effect of circular bridge piers with different inclination angles toward downstream on scour. Indian Academy of Sciences (SADHANA), 41:75-86.
  5. Shukry A, (1950). Flow around bends in an open flume. Transactions of the American Society of Civil Engineers, 15(1):751-779.
  6. Booij R, (2003). Measurements and large eddy simulations of some curved flumes. Journal of Turbulence, 4(1):8-16.
  7. Najafzadeh M, Barani GA, (2014). Experimental study of local scour around a vertical pier in cohesive soils. Scientia Iranica, Trans A, 21(2):241–250.
  8. Blanckaert, K., Graf, W.H. (1999). Outer-bank cell of secondary circulation and boundary shear stress in open-channel bends. InProc. 1st RCEM symp, pp:533-543.
  9. Wildhagen j., Applied Computational Fluid Dynamics with sediment Transport in a Sharply Curved Meadering Channel, Institute for Hydromechanics, Germany, University of Karlsruhe (TH), 2004.
  10. Vaghefi M, Tabib Nazhad Motlagh MJ, Hashemi SSH, Moradi S, (2018). Experimental study of bed topography variations due to placement of a triad series of vertical piers at different positions in a 180° bend. Arabian Journal of Geosciences, 11(5).
  11. Georgiadou AD, Smith KVH, (1986). Flow in curved converging channel. Journal of Hydraulic Engineering ASCE, 112(6):476-496.
  12. Tabarestani MK, Zarrati AR, Mashahir MB, Mokallaf E, (2015). Extent of riprap layer with different stone sizes around rectangular bridge piers with or without an attached collar. Scientia Iranica. Transaction A, Civil Engineering, 22(3):709-716.
  13. Ghodsian M, Mousavi SK, (2006). Experimental study on bed scour in a 90O channel bend. International Journal of Sediment Research, 21(4):321-328.
  14. Ghobadian R, Mohammadi K, (2011). Simulation of subcritical flow pattern in 180° uniform and convergent open-channel bends using SSIIM 3-D model. Water Science and Engineering. 4(3):270-283.
  15. Mansuri AR., 3-D Numerical Simulation of Bed Changes in 180 Degree Bends, M.S. Dissertation. Tarbyat Modares University, Tehran, Iran, 2006.
  16. Gholami A, Akhtari AA, Minatour Y, Bonakdari H, Javadi AA, (2014). Experimental and numerical study on velocity fields and water surface profile in a strongly-curved 90° open channel bend. Engineering Applications of Computational Fluid Mechanics (EACFM), 8(3):447−461.
  17. Abdallah Mohamed Y, Mohamed Abdel-Aal G, Hemdan Nasr-Allah T, Shawky A, (2016). Experimental and theoretical investigations of scour at bridge abutment. Journal of King Saud University – Engineering Sciences, 28(1):32–40.
  18. Akib SH, Basser H, Karami H, Jahangirzadeh A, (2014). Retrofitting of Bridge Piers against the Scour Damages: Case Study of the Marand-Soofian Route Bridge. World Academy of Science, Engineering and Technology, International Journal of Civil, Architectural Science and Engineering, 8(1):56-60.
  19. Ehteram M, Mahdavi Meymand A, (2015). Numerical modeling of scour depth at side piers of the bridge. Journal of Computational and Applied Mathematics. 280:68–79.
  20. Hamidi A, Siadatmousavi SM, (2017). Numerical simulation of scour and flow field for different arrangements of two piers using SSIIM model. Ain Shams Engineering Journal, 9(4):2415-2426.
  21. Emami, Y., Salamatian, S.A., Ghodsian, M. (2008). Scour at cylindrical bridge pier in a 180-degree channel bend. Fourth International Conference on Scour and Erosion, Tokyo, Japan, pp: 256-262.
  22. Masjedi A, Bejestan MS, Kazemi H, (2010). Effect of Bridge Pier Position in a 180 Degree Flume Bend on Scour Hole Depth. Journal of Applied Sciences, 10(8):670-675.
  23. Wang H, Tang H, Xiao J, Wang Y, Jiang S, (2016). Clear-water local scouring around three piers in a tandem arrangement. Science China Technological Sciences, 59(6):888-896.
  24. Khajeh SBM, Vaghefi M, Mahmoudi A, (2017). The scour pattern around an inclined cylindrical pier in a sharp 180-degree bend: an experimental study. International Journal of River Basin Management, 15(2):207-218.
  25. Raudkivi AJ, Ettema R, (1983). Clear-water scour at cylindrical piers. Journal of Hydraulic Engineering (ASCE), 109(3):339-350.
  26. Melville BW, Sutherland AJ, (1988). Design method for local scour at bridge piers. Journal of the Hydraulics Division, 114(10):1210-1225.
  27. Guemou B, Seddini A, Ghenim NA, (2016). Numerical investigations of the round-nosed bridge pier length effects on the bed shear stress. Progress in Computational Fluid Dynamics, 16(5):313-321.
  28. Melville BW, Chiew YM, (1999). Time scale for local scour at bridge piers. Journal of Hydraulic Engineering ASCE, 125(1):59-65.
  29. Oliveto G, Hager WH, (2002). Temporal Evolution of Clear-Water Pier and Abutment Scour. Journal of Hydraulic Engineering ASCE, 128(9):811-820.
  30. Olsen NRB, Jimenes OF, Abrahamsen L, Lovoll A, (1999). 3D CFD modeling of water and sediment flow in a hydropower reservoir. International Journal of Sediment Research, pp.16-24.
  31. Olsen, N.R.B., A three-dimensional numerical model for simulation of sediment movements in water intakes with multi block option, Online User’s manual, 2011.