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Variation of Local Friction Factor in an Open Channel Flow

Affiliations

  • Department of Civil Engineering, National Institute of Technology Rourkela - 769008, Odisha, India

Abstract


Objectives: This present paper investigated experimentally on the variation of local friction factor over the cross section in channels of different geometries. The dependency of the variation of friction factor with aspect ratio has been well compared with the results of other researchers and natural river data. Methods/Analysis: Experiments have been conducted on trapezoidal and rectangular open channel for different geometry, hydraulic and roughness conditions. The local friction factors along every vertical interface have been carried out. The actual prediction of boundary shear stress and depth averaged velocity distribution have been calculated by finding the changes of these indispensible parameters, from wide range of data collected from previous literatures. Also the experimental depth averaged velocity and boundary shear stress have been carried out for assessing the friction factor. Findings: The global friction factor fg and local friction factors fl were calculated based on the measured depth-averaged velocity and boundary shear stress. The local friction factor does not remain constant across the channel as it depends upon the geometry and roughness parameter. The paper describes the variation of friction factor for both smooth and rough channels under different flow condition. Local boundary shear stress around the wetted perimeter τb, and depth averaged velocity, Ud, data are used to evaluate local friction factor, fl. Applications/Improvement: Local friction factor variation analysis is a very rare factor that few researchers are taken into consideration. But it has a more importance for flow characteristics which is studied in this paper.

Keywords

Boundary Shear Stress, Depth Averaged Velocity, Eddy Viscosity, Local Friction Factor.

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References


  • Mohanty PK, Khatua KK. Estimation of discharge and its distribution in compound channels. Journal of Hydrodynamics, Ser. B. 2014 Feb 28; 26(1):144–54.
  • Yang S, Hu J, Guo YK., Li, D., & Wang, X. Study of flow resistance in open channels. River flow 2010: proceedings of the International Conference on Fluvial Hydraulics; Braunschweig, Germany. 2010 Sep 8-10.
  • Mohammadi, M. Local and global friction factor in a channel with v-shaped bottom. International Journal of Engineering-Transactions B: Applications. 2008; 21(4):325.
  • Rameshwaran P, Shiono K. Depth-averaged modelling of overbank flow in meandering channels. River Flow 2004: Proceedings of the Second International Conference on Fluvial Hydraulics; 2004 Jun 23-25; Napoli, Italy: CRC Press; 2004 Jun. p. 329.
  • Fernandes JN, Leal JB, Cardoso AH. Improvement of the lateral distribution method based on the mixing layer theory. Advances in Water Resources. 2014; 69:159–67.
  • Chlebek J. Modelling of simple prismatic channels with varying roughness using the SKM and a study of flows in smooth non-prismatic channels with skewed floodplains [Doctoral dissertation]. University of Birmingham; 2009.
  • Yen BC. Open channel flow resistance. Journal of Hydraulic Engineering. 2002; 128(1):20–39.
  • Simoes FJ. Flow resistance in open channels with fixed and movable bed. 2nd Joint Federal Interagency Conference; Las Vegas. 2010.
  • Azarang F. Mathematical model for evaluating of sediment transport (Case study: Karkheh River in Iran). Indian Journal of Science and Technology. 2015 Sep 16; 8(23).
  • Patel VC. Calibration of the Preston tube and limitations on its use in pressure gradients. Journal of Fluid Mechanics. 1965; 23(01):185–208.
  • Atabay S. Stage-discharge, resistance and sediment transport relationships for flow in straight compound channels [Doctoral dissertation]. University of Birmingham; 2001.
  • Tang X. Derivation of the wave speed-discharge relationship from cross-section survey for use in approximate flood routing methods; 1999.

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