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

由于近年来河道整治的广泛性，我们需要更多地了解各种糙率下的水流结构。山区河流治理实际上需要对小淹没水流的认识。为了设计各种类型的河流建筑物，水流必须经历不同的糙率空间变化模式，因此必须研究糙率空间变化的紊流过渡过程。本研究采用理论分析和室内基础实验相结合的方法，结合湍流的实测资料，对河流生态环境的改善、植被对水流的影响进行了研究。最近发展的风速计和数据记录和处理系统使现场测量相对容易。我们开发了一套利用电磁风速仪进行湍流测量的系统，并在河流或灌溉渠中仔细选择了测量点。选择了相对淹没度小的水流、斜置粗糙度上的六角流体运动、植物上的水流、河床粗糙度空间变化的水流、断面上有植物带的水流，并将野外和实验室的测量结果进行了比较，以证实湍流现象的相似性。本文利用野外和实验室获得的有价值的资料，通过资料分析，并与实验室资料和解析或数值方法的结果进行比较，研究了糙率型式对明渠水流的影响。

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.