An investigation of the effect of suction and injection in open channel flow

The effect of suction and injection in modifying the hydraulic characteristics of a typical open channel flow was assessed through the application of particle image velocimetry. Both downward (suction) and upward (injection) seepage were found to modify the time-mean velocity profile of the channel flow. However, suction was more effective in modifying the flow compared to the equivalent amount of injection. A vortex identification algorithm was applied on the velocity field to study the effect of seepage on the vortex population in the channel flow. Suction reduces the number of vortices in the flow. At the same time, the prevalent size of the vortices decreases, and they become stronger. Injection, on the other hand, has a very weak effect of the same sense compared to the equivalent amount of suction.