Abstract Particle Tracking Velocimetry (PTV) is applied to measure the flow in an oscillating grid stirred tank filled with either water or shear thinning dilute polymer solutions (DPS) of Xanthan Gum (XG). There are many interests of studying turbulence in such complex non-Newtonian fluids (e.g. in the pharmaceutical, cosmetic, or food industry), and grid stirred tanks are commonly used for fundamental studies of turbulence in Newtonian fluids. Yet the case of oscillating grid flows in shear thinning solutions has been addressed recently by Lacassagne et al. (Exp Fluids 61(1):15, Phys Fluids 31(8):083102, 2019a, b), with only a single two dimensional (2D) Particle Image Velocimetry (PIV) characterization of mean flow and turbulence properties in the central vertical plane of the tank. Here, PTV data processed by the Shake The Box algorithm allows for the time resolved, three dimensional (3D) 3 components (3C) measurement of Lagrangian velocities for a large number of tracked particles in a central volume of interest of the tank. The possibility of projecting this Lagrangian information on an Eulerian grid is explored, and projected Eulerian results are compared with 2D PIV data from the previous work. Even if the mean flow is difficult to reproduce at the lowest polymer concentrations, a good agreement is found between measured turbulent decay laws, thus endorsing the use of this 3D-PTV metrology for the study of oscillating grid turbulence in DPS. The many possibilities of further analysis offered by the 3D3C nature of the data, either in the original Lagrangian form or in the projected Eulerian one, are finally discussed. Graphic Abstract

中文翻译：

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水和聚合物溶液中振荡网格湍流的 PTV 测量

摘要 粒子跟踪测速 (PTV) 用于测量装有水或黄原胶 (XG) 的剪切稀化稀聚合物溶液 (DPS) 的振荡网格搅拌罐中的流动。研究这种复杂的非牛顿流体中的湍流有很多兴趣（例如，在制药、化妆品或食品工业中），网格搅拌罐通常用于牛顿流体中湍流的基础研究。然而，最近 Lacassagne 等人已经解决了剪切稀化溶液中振荡网格流的情况。(Exp Fluids 61(1):15, Phys Fluids 31(8):083102, 2019a, b)，只有一个二维 (2D) 粒子图像测速 (PIV) 表征中心垂直方向的平均流动和湍流特性坦克的平面。这里，由 Shake The Box 算法处理的 PTV 数据允许对罐的感兴趣的中心体积中的大量跟踪粒子的拉格朗日速度进行时间分辨、三维 (3D) 3 分量 (3C) 测量。探索了将拉格朗日信息投影到欧拉网格上的可能性，并将投影的欧拉结果与之前工作的 2D PIV 数据进行比较。即使在最低聚合物浓度下难以重现平均流量，在测量的湍流衰减定律之间也发现了良好的一致性，因此支持使用这种 3D-PTV 计量学来研究 DPS 中的振荡网格湍流。最后讨论了数据的 3D3C 性质提供的进一步分析的许多可能性，无论是原始拉格朗日形式还是投影的欧拉形式。