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Experiments on turbidity current regimes in a straight open channel

Keshtkar, S ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.1061/41173(414)422
  3. Publisher: 2011
  4. Abstract:
  5. The present study has been conducted to investigate the effect of inlet flow regimes on vertical velocity and concentration profiles of the turbidity current. Experiments carried out on small scale channel and Kaolin with a density of 2.65 kg/m3 and a mean particle diameter of 4.5 μm, was used to generate the currents. Velocities were obtained at a rate of 10 Hz using an acoustic Doppler velocimeter. Using the siphon sampling approach, the acoustic backscattering intensity was calibrated and concentration was determined using a backscattering analysis. Results showed that the ratio of maximum velocity height to the height of the current was around 0.4-0.5 in sub- and super-critical regimes. Equivalent height of average velocity was observed about 0.8 times of the depth averaged one. The average concentration was observed at the equivalent height of 0.35-0.5 times of current's thickness. The inlet concentration ratios were not affected on the maximum velocity in sub-critical current regime. To increase the gate inlet height was significantly affected on the maximum velocity and the thickness of outer region was decreased in lower concentration. By increasing the gate inlet height two different trends including the smooth profiles and stepped profiles were observed in the super- and sub-critical inlet current regimes, respectively. The channel bed slope was dramatically decreased the velocity maximum height in the lower inlet sediment concentrations but were not affective in concentration higher than 4.2 kg/m3. Also the non-dimensional relationships were proposed in exponential forms that shown a good agreement with the experimental data
  6. Keywords:
  7. A-density ; Acoustic backscattering ; Acoustic Doppler velocimeter ; Average concentration ; Average velocity ; Backscattering analysis ; Channel bed ; Concentration profiles ; Experimental data ; Exponential form ; Flow regimes ; Inlet concentration ; Inlets (waterway) ; Maximum velocity ; Mean particle diameter ; Open channels ; Sediment concentration ; Small scale ; Straight open channels ; Sub-critical ; Super-critical ; Turbidity current ; Velocity profile ; Vertical velocity ; Anoxic sediments ; Backscattering ; Bearings (structural) ; Concentration (process) ; Experiments ; Inlet flow ; Kaolin ; Ocean currents ; Open channel flow ; Sediment transport ; Sustainable development ; Turbidity ; Velocity ; Water resources
  8. Source: World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress, 22 May 2011 through 26 May 2011 ; May , 2011 , Pages 4047-4064 ; 9780784411735 (ISBN)
  9. URL: http://ascelibrary.org/doi/abs/10.1061/41173%28414%29422