Abstract:
This laboratory study focused on the effect of a submerged vane-field on the flow pattern
and bed morphology near and inside the entrance reach of a movable bed 90 lateral diversion. The
system was modelled under live bed conditions for a water discharge ratio of 0.2. Two experiments
were run until bed equilibrium was reached: with and without a vane-field installed close to the
diversion entrance to control the transfer of sediments into the diversion channel. The equilibrium
bed morphology and the associated 3D flow field were measured in great detail. The bed load
diverted into the diversion was reduced by approximately one quarter due to the action of the
vane-field. The vanes prevented the formation of the diversion vortex in the main channel, upstream
of the diversion’s entrance, thus contributing to that decrease. They also created a main channel
vortex that started at the most upstream vanes and further decreased the amount of bed load entering
the diversion. The flow separation zone inside the diversion was larger with vanes, but conveyance
was balanced through a slightly deeper scour trench therein. The flow structures described were
confirmed through the measurements of the turbulent kinetic energy.
