Abstract
In this paper, experiments were conducted in the confluence with a training dike to investigate the interaction between vertical and longitudinalvortices, sediment discharge and the three-dimensional characteristics of the turbulence produced from the merging of two parallel streams with different flow discharge. The distribution of primary flow velocity, secondary currents and bed load were examined in detail by comparing with the two-dimensional turbulent mixing layer behind the thin flat plate.
The experimental results showed that the secondary currents with a vortex diameter of about a flow depth existed in the confluence and they developed due to the interaction of corner secondary currents during the merging process and received effects of vertical vortices within the mixing layer. In addition, the sand ridges, which are defined as sand wave with elongate ridges parallel to the main stream, were formed at even number multiple of a flow depth distant from the plate and downstream position behind it.
