The turbulent structure of a channel flow of Xanthan Gum (XG) polymer solution is experimentally investigated and compared with water flow at a Reynolds number of Re = 7200 (based on channel height and properties of water) and Reτ = 220 (based on channel height and friction velocity, uτ0). The polymer concentration is varied from 75, 100, and 125 ppm to reach the point of maximum drag reduction (MDR). Measurements are carried out using high-resolution, two-component Particle Image Velocimetry (PIV) to capture the inner and outer layer turbulence. The measurements showed that the logarithmic layer shifts away from the wall with increasing polymer concentration. The slopes of the mean velocity profile for flows containing 100 and 125 ppm XG are greater than that measured for XG at 75 ppm, which is parallel with the slope obtained for deionized water. The increase in slope results in thickening buffer layer. At MDR, the streamwise Reynolds stresses are as large as those of the Newtonian flow while the wall-n...

中文翻译：

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含有刚性聚合物的非牛顿溶液的湍流结构

通过实验研究黄原胶 (XG) 聚合物溶液通道流的湍流结构，并与雷诺数 Re = 7200（基于通道高度和水的性质）和 Reτ = 220（基于通道高度）下的水流进行比较和摩擦速度，uτ0)。聚合物浓度从 75、100 和 125 ppm 不等，以达到最大减阻 (MDR) 点。使用高分辨率、双分量粒子图像测速仪 (PIV) 进行测量以捕获内层和外层湍流。测量结果表明，对数层随着聚合物浓度的增加而远离壁。含有 100 和 125 ppm XG 的流的平均速度剖面的斜率大于在 75 ppm 时测量的 XG 的斜率，这与为去离子水获得的斜率平行。坡度的增加导致缓冲层增厚。在 MDR 中，流向雷诺应力与牛顿流的应力一样大，而壁面...