人ロ魚巣開口部

Recently, bank protection works are undertaken construction in many rivers. People try to keep rivers in a natural environment as much as possible. Under such circumstances, artificial block for fish nest comes to be cQnsidered available. To put it at bank serves as not only bank protection but also ecosystem preservation. We studied having an interest in exchanging fluid between main stream of river and inside of the block, which is one of main functions of the block. When main stream of river flow by the block, turbul.ent shearing layer becomes at pass-through of the block. Many vortexes arise in the layer. From previous reports, those vortexes cause exchanging fluid. We analyzed this system by two experiments, one is visualization for stream, another is measurement of flow velocity. The vortexes arising from the leader of pass-through move to downstream with flow. Then the size of them increases with flow. When they get to near the end of passthrough, they brush against the sidewall of channel and they are broken. At the same instant, the width of turbulent shearing layer is increasing with flow, too. ln such hydraulic phenomenon, the size of vortexes, the width of turbulent shearing layer and other turbulent quantities depend on the value of Froude number.