Experimental Study on the Effects of Artificial Bed Roughness on Instantaneous Velocity Fluctuations of Saline Density Currents

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Article 18, Volume 27, Issue 4, September 2013, Pages 839-849   

Document Type: Research Article

DOI: 10.22067/jsw.v0i0.28206

Authors

P. Varjavand^* ; A. Hosseinzadeh Dalir; M. Ghomeshi; Davoud Farsadi

Abstract

Instantaneous velocity fluctuations are very important insuspended sediment load transportation. In this study experiments were performed toinvestigate the effects of artificial bed roughness on the instantaneous velocity fluctuations of saline density currents. Conic and cylindrical shapes of roughness with three heights were used. Velocity profiles were measured with an acoustic profiler velocity meter. Velocity and concentrationprofiles were measured in 3 and 4 cross-sections, respectively. The results show that increasing inrelative roughness height has a little impact on instantaneous velocity fluctuations in the entrainment region of the body of current. Also results of theinstantaneous velocity fluctuations profile on the rough bed show that turbulence intensity at the boundary of the ambient fluid and body of the current for cylindrical and conic roughness were 48 and 32 percent of shear velocity, respectively.

Keywords

Concentration profile; Dense fluid; Relative roughness; Turbulence intensity; Velocity profile