EFFECT OF LONGITUDINAL BLOCK ON FLOW STRUCTURES AROUND BOX GROYNE

抄録

A box groyne is composed of various types of single groyne to satisfy the different river ecological requirements. Fewer studies are available for the flow structure around box groyne with different single shaped groyne. The flow velocity near typical box groynes with a longitudinal block, which is composed by straight and L-shape groyne, are measured by PIV (Particle Image Velocimetry) under emerged flow in horizontal plane. The paper shows experimental results of flow patterns for this box groyne. Due to the longitudinal block of box groyne limits the generation and development of the large coherent structure in the groyne field, flow periodicity and the capacity of mass exchange with main stream are significantly different between these types of box groyne. The placement of block obviously influences the number and scale of circulating flow inside the box groyne field, because of the distribution difference of vortex structure in longitudinal profile of mixing layer.