Study on Effects of Roughness Patterns on Turbulent Structure though Field Measurements

由于近年来河流治理的广泛目的，我们应该更多地了解具有各种糙率模式的水流结构。事实上，山区河流治理需要对相对淹没程度较小的水流有所了解。在河流中设计各种类型的建筑物时，水流必须经历不同的粗糙度空间变化模式，因此需要研究粗糙度空间变化的紊流瞬变过程。河流治理要特别关注环境，要准确评价河流中的植被流。在本研究项目中，采用了基于理论分析和实验室基础实验的方法，并结合了现场测量的湍流。最近风速计和数据记录和处理系统的发展使现场测量变得相对容易。我们开发了利用电磁风速仪进行湍流现场测量的系统，并精心选择了河流或灌渠中的测量地点。选取了相对淹没度较小的水流、斜排条带水流的面状流体运动、植被水流、床面粗糙度空间变化的水流、横断面上有植被带的水流，并与野外和实验室的测量结果进行了比较，证实了湍流现象的相似性。利用野外和实验室获得的有价值的数据，通过数据分析以及与实验室数据和解析或数值方法的结果的比较，研究了明渠水流中粗糙度形态的影响。

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.