The local scour from flows at downstream of an outlet : Intermittent scour

In previos investigation which is concerned with the local scour in case of the water depth downstream of an outlet was deep sufficiently, it becomes clear that the shape of scoured fall and an increasing rate of maximum scoured depth almost coincide quantitatively theoretical curve based on scour model have been proposed by the auther. In practical case, there are not a little instance of shallow water depth downstream of an outlet, and under such circumstance we often fined the phenomenon that in the process of scour direction of issuing flows turn to upward (separated flow) from downward (reattached flow). The authers called this phenomenon 'intermitent scour' downstream of an outlet. This time we make an experiment of scour from flows downstream of an outlet with systematic change of water depth downstream, and attempt to explain the intermitent scour phenomenon in relation to the propertys of curved jets which reattached to flat plate steped down, and it has been became clear experimentaly that the maximum scoured depth at constant non-dimentional time was so decrease as to shallow the water depth downstream.