Arabian Journal for Science and Engineering

, Volume 41, Issue 4, pp 1199–1213 | Cite as

Comparison of Local Scour Characteristics around Two Eccentric Piers of Different Shapes

  • Subhasish DasEmail author
  • Rajib Das
  • Asis Mazumdar
Research Article - Civil Engineering


Local scour at single pier has been extensively studied by several investigators, but scanty work is available on scour around piers placed in close proximity. The present research is concerned with experimental studies of the formation and characteristics of local equilibrium scour around a set of two identical circular-, square-, and triangular-shaped piers placed in longitudinal direction to the flow with a constant eccentricity (transverse distance). The objective is to see the nature of scour evolved due to the effect of mutual interference of one pier on another with the longitudinal spacing between them varying 0.25, 0.375, 0.5, 0.625, and 0.75 times the scour-affected lengths for a single-pier test. Analysis of the results shows the variations of individual non-dimensional equilibrium scour parameters with the effective pier width (diameter of the smallest circumscribing circle of the pier) and increasing longitudinal spacing between the piers.


Open-channel flow Clear water scour Eccentric pier Characteristic pier width Longitudinal spacing 



Characteristic cross-sectional area of pier inside the water (cm2), \({\pi {b}_{{\rm c}}^{2}}\)


Cross-sectional area of pier (cm2), \({\pi b^{2}}\)


Planner surface area of equilibrium scour hole (cm2)


Pier diameter or width (cm)


Characteristic pier width (cm), b e K s


Effective pier width (cm)


Equilibrium scour depth (cm)


Maximum equilibrium scour depth (cm)


Median diameter of sand (mm)


Center-to-center distance between the front and rear piers (cm), 3b


Froude number of flow, \({U{/}\sqrt{gh}}\)


Approaching flow depth (cm)


Ratio of the scour depth for any pier to that for the circular pier


Longitudinal spacing (along the flow) between the front and rear piers (cm)


Maximum equilibrium scour length for two-pier arrangement (cm)


Maximum net scour length for two-pier arrangement (cm), l sml


Maximum equilibrium scour length for single pier (cm)


Maximum equilibrium length of sediment transportation (cm)


Correlation coefficient


Hydraulic radius (cm)


Flow Reynolds number, UR


Pier Reynolds number, Ub


Critical velocity (cm/s)


Shear velocity (cm/s)


Depth-averaged approaching flow velocity (cm/s)

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Characteristic volume of pier below the water surface level (cm3)

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Volume of pier below the water level (cm3), d sm a p

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Volume of equilibrium scour hole (cm3)


Maximum scour width for two-pier arrangement (cm)


Maximum scour width for single pier (cm)


Mass density of water (kg/m3)

\({\rho_{{\rm s}}}\)

Mass density of sand (kg/m3)

\({\sigma_{{\rm g}}}\)

Geometric standard deviation, \({\sqrt{{d_{84}}/{d_{16}}}}\)


Kinematic viscosity (m2/s)


Angle of repose (deg)


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  1. 1.
    Breusers H.N.C., Nicollet G., Shen H.W.: Local scour around cylindrical piers. J. Hydraul. Res. 15(3), 211–252 (1977)CrossRefGoogle Scholar
  2. 2.
    Raudkivi A.J., Ettema R.: Clear-water scour at cylindrical piers. J. Hydraul. Eng. 109(3), 338–350 (1983)CrossRefGoogle Scholar
  3. 3.
    Melville B.W.: Local scour at bridge abutments. J. Hydraul. Eng. 118(4), 615–631 (1992)CrossRefGoogle Scholar
  4. 4.
    Dey S.: Local scour at piers, part 1: a review of development of research. Int. J. Sediment. Res. 12(2), 23–44 (1997)Google Scholar
  5. 5.
    Hoffmans G.J.C.M., Verheij H.C.: Scour Manual. A.A. Balkema, Rotterdam (1997)Google Scholar
  6. 6.
    Melville B.W., Coleman S.E.: Bridge Scour. Water Resources Publications, LLC, Colorado (2000)Google Scholar
  7. 7.
    Ataie-Ashtiani B., Beheshti A.A.: Experimental investigation of clear-water local scour at pile groups. J. Hydraul. Eng. 132(10), 1100–1104 (2006)CrossRefGoogle Scholar
  8. 8.
    Khwairakpam P., Ray S.S., Das S., Das R., Mazumdar A.: Scour hole characteristics around a vertical pier under clear water scour conditions. ARPN J. Eng. Appl. Sci. 7(6), 649–654 (2012)Google Scholar
  9. 9.
    Das S., Ghosh R., Das R., Mazumdar A.: Clear water scour geometry around circular piers. Ecol. Environ. Conserv. 20(2), 479–492 (2014)Google Scholar
  10. 10.
    Breusers H.N.C, Raudkivi A.J.: Scouring, IAHR Design Manual. A.A. Balkema, Rotterdam (1991)Google Scholar
  11. 11.
    Richardson E.V., Lagasse P.F.: Stream Stability and Scour at Highway Bridges. ASCE, Tennessee (1998)Google Scholar
  12. 12.
    Gaudio R., Tafarojnoruz A., De B.S.: Sensitivity analysis of bridge pier scour depth predictive formulae. J. Hydroinform. 15(3), 939–951 (2013)CrossRefGoogle Scholar
  13. 13.
    Melville, B.W.: Local Scour at Bridge Sites. Report 117. School of Eng., Univ. of Auckland, New Zealand (1975)Google Scholar
  14. 14.
    Dargahi B.: Controlling mechanism of local scouring. J. Hydraul. Eng. 116(10), 1197–1214 (1990)CrossRefGoogle Scholar
  15. 15.
    Michael S.A., Mohamed G.M., Mohamed S.B.A.M.: Wake vortex scour at bridge piers. J. Hydraul. Eng. 117(7), 891–904 (1991)CrossRefGoogle Scholar
  16. 16.
    Coleman S.E.: Clearwater local scour at complex piers. J. Hydraul. Eng. 131(4), 330–334 (2005)CrossRefGoogle Scholar
  17. 17.
    Ashtiani A.B., Ghorghi B.Z., Beheshti A.A.: Experimental investigation of clear-water local Scour of compound piers. J. Hydraul. Eng. 136(6), 343–351 (2010)CrossRefGoogle Scholar
  18. 18.
    Das S., Ghosh S., Mazumdar A.: Kinematics of horseshoe vortex in a scour hole around two eccentric triangular piers. Int. J. Fluid Mech. Res. 41(4), 296–317 (2014)CrossRefGoogle Scholar
  19. 19.
    Das R., Khwairakpam P., Das S., Mazumdar A.: Clear-water local scour around eccentric multiple piers to shift the Line of sediment deposition. Asian J. Water Environ. Pollut. 11(3), 47–54 (2014)Google Scholar
  20. 20.
    Sumner D., Wang S.S.T., Price S.J., Paidoussis M.P.: Fluid behavior of side-by-side circular cylinders in steady cross-flow. J. Fluids Struct. 13(3), 309–338 (1999)CrossRefGoogle Scholar
  21. 21.
    Akilli H., Akar A., Karakus C.: Flow characteristics of circular cylinders arranged side-by-side in shallow water. Flow Meas. Inst. 15(4), 187–189 (2004)CrossRefGoogle Scholar
  22. 22.
    Elliott K.R., Baker C.J.: Effect of pier spacing on scour around bridge piers. J. Hydraul. Eng. 111(7), 1105–1109 (1985)CrossRefGoogle Scholar
  23. 23.
    Raudkivi A.J.: Loose Boundary Hydraulics. A.A. Balkema, Rotterdam (1998)Google Scholar
  24. 24.
    Graf W.H.: Fluvial Hydraulics, Flow and Transport Processes in Channels of Simple Geometry. Wiley, Great Britain (2003)Google Scholar
  25. 25.
    Das S., Das R., Mazumdar A.: Comparison of characteristics of horseshoe vortex at circular and square piers. Res. J. Appl. Sci. Eng. Technol. 5(17), 4373–4387 (2013)Google Scholar
  26. 26.
    Das S., Das R., Mazumdar A.: Circulation characteristics of horseshoe vortex in scour region around circular piers. Water Sci. Eng. 6(1), 59–77 (2013)Google Scholar
  27. 27.
    Das S., Midya R., Das R., Mazumdar A.: A study of wake vortex in the scour region around a circular pier. Int. J. Fluid. Mech. Res. 40(1), 42–59 (2013)CrossRefGoogle Scholar
  28. 28.
    Das S., Das R., Mazumdar A.: Variations of clear water scour geometry at piers of different effective widths. Turkish J. Eng. Environ. Sci. 38(1), 97–111 (2014)CrossRefGoogle Scholar
  29. 29.
    Yalin M.S.: Mechanics of Sediment Transport. Pergamon, NY (1977)Google Scholar

Copyright information

© King Fahd University of Petroleum & Minerals 2015

Authors and Affiliations

  1. 1.School of Water Resources EngineeringJadavpur UniversityKolkataIndia

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