Experimental Study On Velocity Profiles In Smooth And Rough Channels
An experimental investigation has been carried out in smooth, rough and movable bed to know the difference in
vertical velocity distribution in each case. The classical log law is usually applied for every vertical velocity profile. All
measured vertical velocity profiles are found to follow the logarithmic law near the bed. The difference in bed material
influences the shape of this profile. To know the effect of bed materials on the vertical velocity profiles, experimental
investigations has been carried out for different smooth, rough and mobile bed conditions with various flow depths. It has
been studied that due to roughness effect the velocity near bed is decreasing as compared to the velocities near surface. A
reduction in magnitude of near bed turbulence is also observed due to the decrease in velocity in such region in mobile bed.
In mobile bed case due to the flow of bed particles are associated with the momentum for overcoming the resistance
provided by bed. In such cases thevonKarman coefficient existing in logarithmic law decreases due to the upward movement
of the virtual bed and the zero-velocity levels.
Keywords— Velocity profile, mobile bed, logarithmic law, roughness effect, von korman Coefficient.