Water circulation induced by a centrifugal water streamer in rectangular reservoirs

Abstract

The water velocity field in a rectangular reservoir driven by a previously unexplored water streamer is investigated experimentally and numerically. Firstly, the velocity field on the water surface induced in a rectangular reservoir is estimated from trajectories of floating passive tracers. Secondly, the velocity at the several fixed points below the surface is directly measured with the aid of an electro-magnetic velocimetry. These measurements elucidate that the streamer activates an underwater circulation between the surface and the bottom in the reservoir. Additionally, a numerical simulation is examined to realise the induced three-dimensional flow below the water surface. The obtained results provide an evidence that the induced flow structure is three-dimensionally spiral, which is distinct from that induced by the water streamers traditionally utilized in aquacultural reservoirs. The investigated streamer may be utilized for the purpose to particularly enhance the underwater vertical mixing in aquacultural reservoir or purification plant.