Abstract
A lot of sediments are often captured in the dead water zone such as an embayment. It is well known that a velocity difference between the main-channel and the side cavity induces a shear instability. Additionally, large-scale horizontal circulations are also formed in the whole cavity region. These multiscale turbulent vortices contribute to mass transfer through a mainstream / embayment boundary and a local sedimentation in the cavity. When the bed configuration varies in space and time, they give striking impacts on hydraulic characteristics. However, the relation between the local sedimentation and the distributions of mean velocity and turbulence is still poorly understood. In the present study, velocity measurements are conducted in a smooth bottom condition and movable one in order to consider how the turbulence structure and exchange properties changes.
