抄録
In natural river flow conditions, vortices generated near the river bed occasionally reaches the water surface and detected as boil vortices. When viewed from an oblique angle we can find that such boil vortices generate surface ripples propagating in the outward direction moving with the surface flow, which can be used as tracer of surface flow measurements by imaging technique such as LSPIV. However, the characteristics of boil vortices are not fully understood so far mainly due to the difficulty in measuring surface flow fields. In this research, experiments using a laboratory flume are conducted to make clear the flow feature of the boil vortices generated by a single square rod. Measurements are performed using a high-vision camcorder and PIV with the erroneous vector correction algorithm proposed by the authors. It was made clear that boil vortices locally decelerate the surface flow. A method for measuring the boil vortex scale is also proposed.
