To investigate the influence of fully-covered artificial ecological floating islands on hydrodynamic characteristics of open channel flows,flume experiments with fully-covered floating islands are conducted in this study.Foam boards and wooden sticks are used to mimic the floating structure and vegetation roots respectively,with ADV used to measure the turbulent characteristics of flows.In this study,flows with full-covered ecological floating islands are vertically divided into the gap layer close to the flume bottom and the floating island layer above.Thus,the two-layer models for the vertical distribution of longitudinal velocities and Reynolds stress are established.The vertical distribution laws for the longitudinal,transverse and vertical turbulent intensities are obtained,which reveal that the three turbulent intensities achieve the maximum value at the bottom of the floating island layer.By adopting the concept of mixing layers,the formula for invasion depth which is suitable for different submergence is obtained.In addition,based on the measured flow fields,the spectrum analysis finds that shear vortices form at the interface of the two layers,and the floating island layer is mainly affected by the stem-scale vortices;the quadrant analysis finds that in the gap layer,the introverted interaction effects are stronger than the extroverted interaction effects,and vice versa in the floating island layer.
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