Author(s): Kiyosi Kawanisi; Ryouhei Shiozaki
Linked Author(s): Kiyoshi Kawanishi
Keywords: Settling velocity; Turbulence; Coherent motion; Open channel flow; Hydraulic experiment; Acoustic Doppler velocimeter
Abstract: The mean settling velocity of solid particles in open-channel turbulent flows have been examined. The settling velocities were measured by using an acoustic Doppler velocimeter. The results indicate that the mean settling velocity is increased by relatively strong turbulence as shown in previous work in homogeneous isotropic turbulence. The settling velocity was increased by a factor of 6. At low turbulence intensity, the heavy particles settle at rate equal to the settle rate in a still water. At intermediate turbulence intensity, it seems that the settling data bifurcate, i. e., the heavy particles with the large Stokes response time tend to be slowed, while settling velocity of the particles with small response time are increased. In order to examine the effects of coherent motion on the settling velocity, quadrant analysis was conducted. The results suggest that more particles tend to be on the enhanced side of vortices than the suppressed side.
Year: 2005