Variations of Effectiveness of a Vertical-barrier-type Reflection Wave Dissipater with Tidal Level and Possible Counter Measures

We have already presented a new type of reflection wave dissipater, which has a curtain wall in front of the vertical seawall. The mechanism of the dissipater is to enhance vortex flows around the lower edge of curtain wall by the use of piston mode wave resonance in the water chamber. In order to expand the usage of the dissipater to the sea with comparatively large tidal difference, performance of the dissipater for various water levels is examined extensively . As a countermeasure to the variation of performance with tidal difference, we propose two different types of dissipaters, i. e., a vertically inclined wall unit and a combination of different draft wall units along the shore. Effectiveness of such dissipaters is examined experimentally and theoretically for various water levels.