Analysis of Overflow Characteristics around a Circular-Crested Weir by Using Numerical Model

수치모의를 이용한 원형위어의 월류흐름 특성 해석

Kim, Dae-Geun

  • Received : 2014.12.03
  • Accepted : 2016.03.02
  • Published : 2016.04.15


The present study used the hydrodynamic numerical model, with the Reynolds-averaged Navier-Stokes equations (RANS) as its governing equations, to analyze overflow characteristics such as the discharge coefficient of circular-crested weir and the flow velocity and pressure distribution of weir crest. The simulation results well reproduced the overflow characteristics of the overfall of circular-crested weir both qualitatively and quantitatively. As for the discharge coefficient, rational results were yielded by the discharge coefficient equation proposed by Hager(1985) in the $H_1/R_b<0.58$ and by the discharge coefficient equation proposed by Samani and Bagheri(2014) in the $H_1/R_b>0.58$, respectively. Because most existing discharge coefficient equations were developed by disregarding the effects of the approach velocity, when they are applied, it is necessary to evaluate the effects of the approach velocity on the overflow head beforehand.


circular-crested weir;discharge coefficient;overflow head;RANS;weir crest


  1. Bagheri, S., Heidarpour, M. (2010). Velocity distribution over cylindrical weirs, J. Hydraulic Res., 48(4), 515-520.
  2. Bijankhan, M., Stefano, C.D., Ferro, V., Kouchankzadeh, S. (2014). New stage-discharge relationship of weirs of finite crest length, J. Irrig. Drain. Eng. 140(3), 06013006(6)
  3. Bos, M.G. (1976). Discharge measurement structures, Report No. 4, ILRI, Wageningen, Netherlands.
  4. Flow Science (2007). Flow-3D (Theory Manual), Los Alamos, NM.
  5. Hager, W.H. (1985). Critical flow condition in open channel hydraulics, Acta Mech., 54(3-4), 157-179.
  6. Hager, W.H. (1999). Wastewater hydraulics, Springer, Berlin.
  7. Heidarpour, M., Chamani, M.R. (2006). Velocity distribution over cylindrical weirs, J. Hydraulic Res., 44(5), 708-711.
  8. Ho, D.K.H., Boyes, K.M., Donohoo, S.M. (2001). "Investigation of spillway behavior under increased maximum flood by computational fluid dynamics technique", 14th Australasian Fluid Mechanics Conference, Adelaide University, Adelaide, Australia.
  9. Kim, D.G. (2013). Hydraulic characteristics in the movable venturi flume with circular cone, J. of Korean Society of Water and Wastewater, 27(2), 177-184.
  10. Kim, D.G., Kim, S.M., Park, W.C. (2010). Numerical analysis of flow and settling efficiency in a sedimentation basin, J. of Korean Society of Water and Wastewater, 24(6), 713-722.
  11. Kim, D.G., Lee, J.H., Seo, I.W. (2004). A numerical simulations on the flow over ogee spillway with pier, J. of Korea Water Resources Association, 37(5), 363-373.
  12. Kim, D.G., Choi, J.U., Kim, C.S., Lee, J.W. (2005). Design by using hydraulic and numerical model experiment - Case study of HwaBuk multipurpose dam, J. of Korea Water Resources Association, 38(3), 179-188.
  13. Ramamurthy, A.S., Vo, N.D. (1993). Characteristics of curcular-crested weir, J. Hydraulic Eng., 119(9), 1055-1062.
  14. Samani, A.K., Bagheri, S. (2014). Discharge coefficient of circular-crested weirs based on a combination of flow around a cylinder and circulation, J. Irrig. Drain. Eng., 140(5), pp. 04014010(6).
  15. Savage, B.M., Johnson, M.C. (2001). Flow over ogee spillway: Physical and numerical model case study, J. Hydraulic Eng., 127(8), 640-649.
  16. Vo, N.D. (1992). Characteristics of curvilinear flow past circular-crested weirs, Ph. D Thesis, Concordia Univ., Montreal, Canada.
  17. Yakhot, V., Orszag, S.A., Thangam, S., Gatski, T.B., Speziale, C.G. (1992). Development of turbulence models for shear flows by a double expansion technique, Phys. Fluids, 4(7), 1510-1520.