Near-Bed Flow Characteristics of Closed-Conduit Flow Subjected to Suction: Fid-Bau Portal

Near-Bed Flow Characteristics of Closed-Conduit Flow Subjected to Suction

Cao, Deping / Chiew, Yee-Meng

Suction effects on the flow characteristics of closed-conduit flow are experimentally investigated by using the particle image velocimetry technique in this study. The results show that as suction intensity, $I_{s}$ , increases, (1) the streamwise velocity becomes more uniformly distributed, (2) the vertical velocity becomes more negative, and (3) the turbulence intensities and shear stress generally decrease when $0 \leq I_{s} \leq 2.32 %$ before gradually increasing when $I_{s} > 2.32 %$ . A modified log law, which is theoretically derived for the streamwise velocity in closed-conduit flow, fits well with the experimental results. The data related to the longitudinal development of the streamwise velocity profiles show that the profile becomes more uniform as the flow moves farther into the suction zone. This behavior indicates that the distance into the suction zone has an effect on the flow similar to that of suction intensities. Moreover, the turbulent-energy budget conducted reveals that the streamwise and vertical energy fluxes are transported upstream and upward, respectively. Finally, the profiles of turbulent-energy production, dissipation, and diffusion and pressure-energy diffusion become more uniform with increasing $I_{s}$ .