Micro-PIV of viscoelastic fluid flow in microporous media

IF 2.7 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-08-05 DOI:10.1016/j.jnnfm.2024.105295

Victor C. Ibezim , David J.C. Dennis , Robert J. Poole

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引用次数: 0

Abstract

The present experimental investigation combines the bulk flow properties of polymer solutions and measurable rheological parameters as they flow through a distinctive micro-porous structure, with micro-PIV (micro-particle image velocimetry) to measure the velocity distribution and velocity fluctuations within individual pores of a novel porous glass structure. To investigate the effects of fluid elasticity at pore scale, aqueous solutions of a polyacrylamide (PAA) & polyethylene oxide (PEO) in the concentration range of 50–200 ppm, which were characterized in both shear and extensional flows using shear and capillary break-up extensional rheometers (CaBER) respectively, were used as working fluids. The velocity field measurement includes the velocity magnitude and fluctuation intensity in several different pores within the porous material across a Weissenberg number $W i$ range of approximately 0.01 to 1 for each of the test fluids. The global averaged fluctuation intensity increases with $W i$ but the critical value, which indicates the onset of significant unsteadiness (i.e. well above noise floor/Newtonian baseline) within the flow at pore scale gives an approximately constant value of $W i \approx$ 0.4, which is almost 40 times higher than the value that is observed in the pressure-drop measurements for the data to rise above the Newtonian base line. We therefore postulate that the enhanced pressure-drop behaviour of the bulk flow may not be due to local velocity fluctuations within the pores but due to mean flow effects, at least over a significant portion of the data (up to $W i \approx$ 0.4).

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微孔介质中粘弹性流体流动的微观 PIV 分析

本实验研究将聚合物溶液流经独特微孔结构时的体积流动特性和可测量的流变参数与微颗粒图像测速仪（micro-PIV）相结合，测量新型多孔玻璃结构单个孔隙内的速度分布和速度波动。为了研究孔隙尺度上流体弹性的影响，使用了浓度范围为 50-200 ppm 的聚丙烯酰胺（PAA）和样品；聚环氧乙烷（PEO）的水溶液作为工作流体，并分别使用剪切流变仪和毛细管破裂扩展流变仪（CaBER）对剪切流和扩展流进行了表征。速度场测量包括多孔材料内多个不同孔隙中的速度大小和波动强度，每种测试流体的魏森伯格数 Wi 范围约为 0.01 到 1。全局平均波动强度随 Wi 值的增加而增加，但临界值表明孔隙尺度上的流动开始出现明显的不稳定性（即远高于噪声底线/牛顿基线），其近似恒定值为 Wi≈0.4，比在压降测量中观察到的数据高于牛顿基线的值高出近 40 倍。因此，我们推测，大量流动的压降行为增强可能不是由于孔隙内的局部速度波动，而是由于平均流动效应，至少在数据的很大一部分（Wi≈0.4以下）是这样。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Non-Newtonian Fluid Mechanics 物理-力学

CiteScore

5.00

自引率

19.40%

发文量

109

审稿时长

61 days

期刊介绍： The Journal of Non-Newtonian Fluid Mechanics publishes research on flowing soft matter systems. Submissions in all areas of flowing complex fluids are welcomed, including polymer melts and solutions, suspensions, colloids, surfactant solutions, biological fluids, gels, liquid crystals and granular materials. Flow problems relevant to microfluidics, lab-on-a-chip, nanofluidics, biological flows, geophysical flows, industrial processes and other applications are of interest. Subjects considered suitable for the journal include the following (not necessarily in order of importance): Theoretical, computational and experimental studies of naturally or technologically relevant flow problems where the non-Newtonian nature of the fluid is important in determining the character of the flow. We seek in particular studies that lend mechanistic insight into flow behavior in complex fluids or highlight flow phenomena unique to complex fluids. Examples include Instabilities, unsteady and turbulent or chaotic flow characteristics in non-Newtonian fluids, Multiphase flows involving complex fluids, Problems involving transport phenomena such as heat and mass transfer and mixing, to the extent that the non-Newtonian flow behavior is central to the transport phenomena, Novel flow situations that suggest the need for further theoretical study, Practical situations of flow that are in need of systematic theoretical and experimental research. Such issues and developments commonly arise, for example, in the polymer processing, petroleum, pharmaceutical, biomedical and consumer product industries.