Study on time development of horse-shoe vortex diameter and shear stress at bridge pier

Document Type : Research Paper

Author

• Mojtaba Karimaei Tabarestani

Geo-technical and Water engineering Group, Department of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran

Abstract

Horse-shoe vortex at the bridge pier nose is a final result of reverse pressure gradient at the upstream side of pier and river surface. From literature review different ideas about the formation and initiation of horse-shoe vortex at the bridge pier can be found. These ideas indicated that the horse-shoe vortex is formed before the formation of scour hole, exactly when the scour hole forms and after the formation of scour hole. In present study these ideas are examined with different experimental data selected from previous studies. The experimental data includes equilibrium scour hole to examine the size of horse shoe vortex in comparison with final scour depth and time development of local scour depth to study the variation of horse-shoe vortex diameter with time. Results showed that similar to scour depth development, the logarithmic trend of horse-shoe vortex diameter with time tends to an equilibrium value. In addition, the calculated horse-shoe vortex diameter in equilibrium scour hole condition with different methods is a function of different parameters such as sediment size or bridge pier diameter and varies from 0.3 to 3.3 of equilibrium scour hole. Finally, a new method is presented for calculation of bed shear stress at the bridge pier with regard to diameter of horse-shoe vortex. In this method, by increasing the size of horse-shoe vortex, shear stress at the bridge pier decreases from 4 times of upstream shear stress to critical shear stress of stream bed sediment.

Keywords

• Bridge pier
• Horse-shoe vortex
• Shear stress
• Scour depth

20.1001.1.20086377.1399.13.44.5.6

---

References

1)        Alabi, P.D., 2006. Time development of local scour at a bridge pier fitted with a collar. M.Sc thesis, Civil and Geological Eng. Dept., University of Saskatchewan, Canada.

2)        Apsilidis, N., Diplas, P., Dancey, C. L., and Bouratsis, P. 2016. Effects of wall roughness on turbulent junction flow characteristics. Experiments in Fluids, 57(1), 12.

3)        Chiew, Y. M. 1995. Mechanics of riprap failure at bridge pier. Journal of Hydraulic Engineering, 121(9): 635-643.

4)        Guan, D., Chiew, Y. M., Wei, M. and Hsieh, S. C., 2019. Characterization of horseshoe vortex in a developing scour hole at a cylindrical bridge pier, International Journal of Sediment Research, 34(2): 118-124.

5)        Chang,W. Y., Lai, J. S., and Yen, C. L., 2004. Evolution of scour depth at circular bridge piers” Journal of Hydraulic Engineering, 130(9): 905–913.

6)        Chen, Q., Qi, M., Zhong, Q., and Li, D. 2017. Experimental study on the multimodal dynamics of the turbulent horseshoe vortex system around a circular cylinder. Physics of Fluids, 29(1), 015106.

7)        Dargahi B., 1989. The turbulent flow field around a circular cylinder. Experimental Fluids 8(1):1–12.

8)        Das, S., Das, R., and Mazumdar, A., 2013. Comparison of characteristics of horseshoe vortex at circular and square piers. Research Journal of Applied Sciences, Engineering and Technology, 5(17): 4373-4387.

9)        Ettema, R., 1980. Scour at bridge piers. PhD Thesis, Auckland University, Auckland, New Zealand.

10)     Karimaee Tabarestani M., Zarrati A. R., 2012. Effect of collar on time development and extension of scour hole around cylindrical bridge pier. International Journal of Engineering, 25 (1): 11-16.

11)     Karimaee Tabarestani M, Zarrati A. R., 2017. Local scour calculation around bridge pier during flood event. KSCE Journal of Civil Engineering, 21(4): 1462–1472.

12)     Kothyary, U. C., Garde, R. J., and Range Raju, K. G., 1992. Temporal variation of scour around circular bridge pier. Journal of Hydraulic Engineering, 118(8): 1091-1106.

 

13)     Link, O., Gobert, C., Manhardt, M. and Zanke, U., 2008. Effect of the horseshoe vortex system on the geometry of a developing scour hole at a cylinder. Fourth International Conference on Scour and Erosion, 162-168.

14)     Mashahir, M.B., Zarrati, A.R. and Mokallaf, E., 2007. Effect of Bed Shear Stress on Development of Scouring around Bridge Piers Protected by a Collar. Proceeding 32nd Congress, IAHR, Venice, Italy.

15)     Melville, BW. 1975. Local Scour at Bridge Sites. University of Auckland, School of Engineering, Auckland, New Zealand, Rep. No. 117.

16)     Melville, B. W. and Chiew, Y. M.1999. Time scale for local scour at bridge piers. Journal of Hydraulic Engineering, 125(1): 59-65.

17)     Mia, M. F., and Nago, H. 2003. Design method of time-dependent local scour at circular bridge pier, Journal of Hydraulic Engineering, 129(6): 420– 427.

18)     Muzzammil M, Gangadharaiah T., 2003. The mean characteristics of horseshoe vortex at a cylindrical pier. Journal of Hydraulic Research, 41(3):285–297.

19)     Rajeev, K., Amitesh, N., Sangam, S., Gurpreet, S., Jagdeep, S., Vishal, S., Paramveer, S., Akhalesh, S., and Ramandeep, S., 2018. Oil film visualization of horseshoe vortices around surface mounted obstacles, Proceedings for research and innovations in science, engineering and technology, At Jammu, India.

20)     Raudkivi, A. J. 1998. Loose boundary hydraulics, Balkema, Rotterdam. The Netherland.

21)     Schanderl, W., and Manhart, M. 2016. Reliability of wall shear stress estimations of the flow around a wall-mounted cylinder. Computers and Fluids, 128, 16-29.

22)     Schanderl, W., Jenssen, U., Strobl, C., and Manhart, M. 2017. The structure and budget of turbulent kinetic energy in front of a wall-mounted cylinder. Journal of Fluid Mechanics, 827, 285-321.

23)     Tseng, M. H., Yen, C. L. and Song, C. C. S. 2000. Computation of three dimensional flow around square and circular piers. International Journal for Numerical Methods in Fluids 34: 207–227.

24)     Unger J, and Hager WH. 2007. Down-flow and horseshoe vortex characteristics of sediment embedded bridge piers. Experimental Fluids. 42(1):1–19.