An Experimental Study Of Longshore Current Recirculation System

Longshore current is one of the more important nearshore hydrodynamic force, has an important impact on the nearshore sediment transport movement, pollutant dispersion and so on. The biggest difficulty of longshore current indoor physical model tests is water circulation. According to the experimental conditions of State Key Laboratory of Coastal and Offshore Engineering, It designs and produces the flow device which is simple structure, easy installation and removal in this study. The main content includes:(1) Firstly, it describes the longshore current experimental water circulation devices which were used by Delft University of Technology, US Army Engineer Research and Development Center. They used active recirculation system which was driven by pumps, the water cycled from the downstream to the upstream through pipes. The loop method made the experimental results had greatly improved. Compared to passive recirculation system, the longshore uniformity had significantly improved. Passive recirculation system was used by Dalian University of Technology, which means that the longshore current was allowed to passively flow back to the upstream through the channels. The effect of this method was not good, only in the middle part of the terrain along the coast had a more uniform flow, the flow rate became smaller or larger in the upstream and downstream,(2) It designs and produces the flow device which is simple structure, easy installation and removal. The experimental method was active recirculation which driven by high-power pumps. The water flew out in a specific distribution form under the action of the device. It got a variety of current velocity profile types by regulatory role shunt instrument and rectification plank. A flow profile was composed of6deviees, which was used to simulate longshore current velocity profiles.(3) According to the longshore current experiments, this study designed the site layout of the flow device. The whole device flow distribution can be determined according to the needs of the target longshore current, the flow device and the backflow device is connected by water circulation system. This study also shows on-site installation layout of flow device and structure of the controller and connection methods.