抄録
There is a lot of knowledge about head of the groin and between the groins. The influence of a groin reaches to the distant downstream. However there are many unknown things that flow condition and downstream of the groin is influenced by layout of the groin. Purpose of this study analyze flow characteristic of downstream on the single groin and the groins by experiment of different layout. As a result, the form of the separation vortex under the groin has affected structure. For example, since a single groin has the strong flow which goes to the center of a channel, its separated flow region is larger than groins. Therefore, since the momentum transport on boundary of groin region is small, the position which returns to steady flow becomes distant downstream.
