Abstract
In this paper, the experiments were performed to investigate behavior of large scale vortices, the three-dimensional characteristics of the turbulent structure and sand waves in the confluent flow with a training dike, which was produced from the merging of two parallel streams. The results show that the secondary currents with a vortex diameter of about a flow depth exist in the confluence and they develop due to the interaction of corner secondary currents during the merging process. In addition, the three-dimensional characteristics of main flow velocity, Reynolds stresses and turbulent energy are discussed by comparing the confluence flow with the two dimensional turbulent wake behind the thin flat plate.