ABSTRACT
Plastic garbage in the ocean becomes a big problem recently. The main origin of such garbage is the effluent from rivers. The side concavity zone often exists in rivers, and it can be used to collect the floating garbage. In order to capture the floating garbage in riverside concavity zones, spur dikes are used to guide the flow into the concavity zone and capture them at a downstream screen. The experiments were conducted to know the adequate arrangement of the capturing system to get a high capture rate of garbage. PIV method was employed to measure the velocity vectors near the free surface. Plastic balls were put into the water at the upstream of the concavity zone, and the capture rate was measured. In the experiments, the effects of the relative position, the slope of the guiding wall at the upstream concavity zone, and the planar shape of the spur dike were investigated. As a result, the low slope of the guiding wall and a spur dike position at just the upstream wall of the concavity give a favorable flow structure to capture the floating material. It was understood that the lateral velocity distribution along the open boundary was important to raise the capture rate.
