Turbulence in curvilinear bed streams

Anurag Sarma, Mahesh Patel, Bimlesh Kumar

Tuesday 30 june 2015

14:50 - 15:05h at Europe 1 & 2 (level 0)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 6E. Engineering - Computational

This paper describes a laboratory study of dynamics of flow associated with the turbulence parameters in mobile bed channel. The Experiment is conducted for curvilinear mobile bed at threshold condition of flow considering median grain size d50=0.418mm. The 3D velocity is measured with Acoustic Doppler Velocitimeter (ADV) which is working on the principle of Doppler Effect. Based on obtained experimental data between instantaneous velocity and flow depth, turbulence parameters have been analyzed. The von-Karman constant has been found as 0.36 from velocity logarithmic law. Shear velocity (u*=0.01933 m/sec) is calculated through experimentally and shear velocity (u*=0.0192 m/sec) is calculated through Reynolds shear stress by assuming that Reynolds Stress of the flow on the ordinary bed follows a linear law. The vertical distribution of third order moment Mjk(z+) in the mobile bed M30 and M12 start with small positive values near the bed and changing over to negative value but M03 and M21 is negative near the bed. The positive Fku and negative Fkw in near bed flow zone represents the stream wise and downward transport of TKE-flux components respectively while away from the bed , The negative Fku and positive Fkw forming a retardation process with the slowly moving fluid parcel.