Theoretical Analysis and Numerical Simulation of Mechanical Energy Loss of Turbulent Flows in Open-Channel Expansions

Document Type : Research Paper

Authors

Faculty of Civil Engineering, University of Tehran. Tehran, Iran

Abstract

It is a popular fact that mechanical processes are usually accompanied by the dissipation phenomenon. Therefore, it is not possible to retain the initial energy over a temporal period or a local distance without spending additional energy. Because these motions are accompanied by conversion into heat. In other words, due to some factors such as friction, cross-section changes, etc., there are some energy losses that the process is irreversible, and some of the system's energy is mainly dissipated as heat. In the most cases of the open-channel transitions, the energy losses of turbulent flows are so complex that it is not easy to define specific relationships for them, and the energy losses are usually determined empirically or experimentally. Examining how the mechanical energy loss of three-dimensional turbulent flows can be estimated without measurements is one of the important subjects of this paper. In this study, in order to better understand the mechanism of the energy losses, during a journey from hydrodynamics to hydraulics, the process of the energy loss of turbulent flows and its relationship with the turbulence parameters are examined through theoretical analysis and 3-D numerical simulations. The relationship between the mechanical energy loss and the roughness coefficient is further obtained and investigated. The results are presented in the form of the application of the new analytical relationships in open-channel expansions and determining the contribution of the effective parameters of turbulent flows to the energy loss.

Keywords

References

  1. Hager, W. H., (2010). Wastewater hydraulics: Theory and practice: Second edition.
  2. Morris, H. M. and Wiggert, J. M., (1972). Applied hydraulics in engineering, Wiley.
  3. French, R. H., (1986). open-channel hydraulics, MacGraw-Hill.
  4. Chow, V. T., (1959). Open Channel Hydraulics, Mcgraw-Hill Company.
  5. Mahmoudi, M., Tabatabai, M. R. M., and Nadoushani, S. M., (2019). An analytical approach to the estimation of optimum river channel dimensions, Scientia Iranica, 26(3A), pp: 1169–1181.
  6. Nezu, I. and Nakagawa, H., (1989). Turbulent structure of backward-facingstep flow and coherent vortex shedding from reattachment in open chan-nel flows, inTurbulent Shear Flows: Selected Papers From the SixthInternational Symposium on Turbulent Shear Flows, pp: 313–337, Springer, Berlin.
  7. Amara, L., Berreksi, A. and Achour, B., (2017). Quasi-2D model for computation of supercritical free surface flow in sudden expansion, Appl. Math. Model., 46, pp: 396–407.
  8. Haque, A., (2008). Some Characteristics of Open Channel Transition Flow, M.Sc. Thesis, Civil Engineering, Concordia University.
  9. Henderson, F. M., (1966). Macmillan Publishing Co, Inc. New York.
  10. Fouladi Nashta, C. and Garde, R. J., (1988). Subcritical flow in rigid-bed open channel expansions, J. Hydraul. Res., 26(1): pp. 49–65.
  11. Basak, B. C.and Alauddin, M., (2010). Efficiency of an expansive transition in an open channel subcritical flow, DUET Journal, Dhaka Univ. Eng. Technol., 1(1): pp. 27–32.
  12. Najafi-Nejad-Nasser, A., and Li, S. S., (2015). Reduction of flow separation and energy head losses in expansions using a hump. Journal of Irrigation and Drainage Engineering, 141(3): pp. 04014057-1 – 04014057-9.
  13. Artichowicz, W. and Sawicki, J. M., (2017). Determination of mechanical energy loss in steady flow by means of dissipation power, Arch. Hydro-Engineering Environ. Mech., 64(2): pp. 73–85.
  14. Liu, S., Fan, M., and Xue, J., (2014). The mechanical energy equation for total flow in open-channels. Journal of Hydrodynamics, 26(3): pp. 416–423.
  15. Liu, S., and Xue, J., (2016). Theoretical analysis and numerical simulation of mechanical energy loss and wall resistance of steady open-channel flow. Journal of Hydrodynamics, 28(3): pp. 489–496.
  16. Hinze, J. O., (1975). Turbulence McGraw. McGraw-Hill Publishing Co., New York.
  17. Nezu, I. and Nakagawa, H., (1993). Turbulence in open-channel flows, Balkema, Rotterdam: IAHR Monograph.
  18. Førde, O. Ø., (2012). Analysis of the turbulent energy dissipation, M.Sc. Thesis, Norwegian University of Science and Technology.
  19. Wilcox, D. C., (1998). Turbulence modeling for CFD (Vol. 2). DCW industries La Canada, CA.
  20. Pavanelli Lira, V., (2014). Numerical modeling of a 90° open- channel confluence flow using openfoam cfd, M.Sc. Thesis, Federal University of Minas Gerais.
  21. Salih, S. Q., Aldlemy, M. S., Rasani, M. R., Ariffin, A. K., Ya, T. M. Y. S. T., Al-Ansari, N., Yaseen, Z. M., and Chau, K. W., (2019). Thin and sharp edges bodies-fluid interaction simulation using cut-cell immersed boundary method. Engineering Applications of Computational Fluid Mechanics, 13(1): pp. 860–877.
  22. Asnaashari, A., Akhtari, A. A., Dehghani, A. A. and Bonakdari, H., (2018). Effect of Inflow Froude Number on Flow Pattern in Channel-Expansive Transitions, J. Irrig. Drain. Eng., 142, (1); pp. 06015004-1 – 06015004-5.
  23. Abdo, K., Riahi-Nezhad, C. K., and Imran, J., (2018). Steady supercritical flow in a straight-wall open-channel contraction. Journal of Hydraulic Research, 57(5): pp. 647–661.
  24. Versteeg, H. K., and Malalasekera. W., (2016). An Introduction to Computational. Fluid Dynamics. The finite volume method. London, Second Edition.
  25. Celik, I., and Rodi, W., (1984). Simulation of free-surface effects in turbulent channel flows. Physicochemical Hydrodynamics, 5(3–4): pp. 217–227.
  26. Mamizadeh, J., and Ayyoubzadeh, S. A., (2012b). Simulation of flow pattern in open channels with sudden expansions. Research Journal of Applied Sciences, Engineering and Technology, 4(19): pp. 3852–3857.
  27. Mamizadeh, J., and Ayyoubzadeh, S., (2012a). Numerical and Experimental Simulation of Flow Pattern in Sudden and Gradual Canal Expansions, Journal of Engineering and Applied Sciences, 7(6): pp. 389-394.
  28. Zhou, J. G., (1995). Velocity-depth coupling in shallow-water flows, Journal of Hydraulic Engineering, 121(10), 717–724.
  29. Graber, S. D., (1982). Asymmetric flow in symmetric expansions, J. Hydraul. Div., vol. 108(10): pp. 1082–1101.

Files

Share

How to cite

Statistics