Turbulence characteristics of flow over the degraded cohesive bed of clay–silt–sand mixture

Abstract

This paper presents experimental results of turbulence characteristics of flow using Acoustic Doppler Velocimeter over the degraded channel bed made of clay–silt–sand mixture in which clay varied as 0, 30, and 50%. The vertical distribution of velocity, turbulence intensity, turbulence kinetic energy, and Reynolds shear stress has been made at different sections of channel bed. The resultant flow velocity was found to be reversal near the bed surface especially in the upstream of working section. Normalized turbulence intensity found to be maximum around the initial bed level over the degraded bed corresponding to 30 and 50% clay content, whereas the maximum value lies below the initial bed level for 0% clay content especially at upstream sections. The variation in the value of turbulence intensity across the depth of flow was found to be more at upstream section and reduces as moved toward downstream section. The position of occurrence of minimum value of normalized Reynolds shear stress was noticed differently for 0% clay content bed when compared to that of 30 and 50% clay content in the bed especially at upstream sections.