| Research Abstract |
Because of recent wide purpose of river improvements, we should know more about the flow structure with various patterns of roughness. In fact, river improvement in mountain regions needs the knowledge on the flow with small relative submergence. For designing various types of structures in rivers, the flow must experience various patterns of spatial change of roughness, and thus the transient process of turbulent flow for spatial change of roughness should be studied. The river improvement with special respect with environments, the flow with vegetation should be accurately evaluated.
In this research project, the approach based on theoretical analysis and fundamental experiments in laboratories was coupled with field measurements of turbulence. Recent development of anemometers and data-recording and processing system have made field measurements comparatively easy. We have developed the system of field measurements of turbulence with aid of electromagnetic anemometers, and carefully selected the measuring sites in rivers or irrigation canals. The flow with small relative submergence, hekicoidal fluid motion of flow over skew arrangement of strip roughness, the flow over vegetation, the flow with spatial change of bed roughness, the flow with vegetation zone in a cross section have been selected and the measurements in fields and in laboratories have been compared to confirm the similarity of the turbulent phenomena. With valuable data obtained in fields and laboratories, the effects of roughness patterns in open-channel flows have been investigated through data analyses and comparison of the data with laboratory data and the results of analytical or numerical approaches.
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