It is a well known experimental fact that the undulation such as sand-ripples or antidunes are formed on the bed surface composed of fine sand, corresponding to the flow characteristics of open channel flow.O In this case, as the mechanical effects of the bed undulationes stated above, a kind of periodic motion is superposed on the flow, and accordingly the water surface undulates periodically. On the other hand, the mechanical effects of this surface undulationes are surperposed on these undulating bed surfaces as another kind of periodic motion. The wave generated in open sea propagates upstream through an estuary. Accordingly the incoming wave is superposed on the flow stated above as a forced oscillation. Both of these phenomena are in the coexistence system of flow and waves in the open channel flow. In this paper, as the first step to study the subjects stated above, the author treats the problem of the coexistence system in the case when the forced oscillation of water surface is superposed on the open channel flow with fixed bed, and analyzes theoretically and experimentally the mechanical properties of the reciprocal action between flow and waves.
Effects of Water Surface oscillation on Flow Characteristics in Open-channel Flow with Spur Dikes
