Development of Large Scale Vortex around T-type and L-type Groynes

There are several types of groyne, such as T-type and L-type groynes, that have been constructed worldwide in accordance with different river environments. However, little information has been obtained on the structures of large-scale vortex-development around differently shaped groynes. Because these flow structures are expected to significantly affect the formation of sand waves further downstream, this phenomenon should be considered systematically and in detail. To reveal such flow effects, flow is visualized around several types of groyne by means of particle tracking velocimetry, which was developed especially for estimating large-velocity difference. To discuss the flow pattern around the groynes, Analyses of conditional sampling and spectral distribution and Weiss function are applied to reveal the coherent structures. The results show strong and large vortex development from the tips of groynes toward downstream. The differences in flows around several types of groyne are the distributions of large areas of coherent vortex downstream.