Quantitative description of polymer drag reduction: Effect of polyacrylamide molecular weight distributions

IF 2.7 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-01-17 DOI:10.1016/j.jnnfm.2024.105185

Lukas Brandfellner , Emina Muratspahić , Alexander Bismarck , Hans Werner Müller

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Abstract

The effect of molecular weight distribution of polyacrylamide (PAAm) on drag reduction was studied in two flow geometries. Commercial PAAm with different weight averaged molecular weights (M_w = 5 × 10⁵ to 1.8 × 10⁷ g/mol) were investigated in turbulent pipe and rotational flows. Comparison of PAAm with different molecular weight distributions showed that drag reduction is not only a function of the averaged molecular weight. Broader polymer molecular weight distributions provided increased drag reduction over polymers of same average molecular weight but with a more narrow distribution. The role of distribution widths is of significance as polymer degradation in turbulent flows causes narrowing of the molecular weight distributions. Multiple linear regression was employed to connect weight fractions of polyacrylamide with drag reduction. Multiple linear regression was successfully applied to describe drag reduction in turbulent pipe and rotational flows indicating that drag reduction can be quantitatively derived from the molecular weight distribution of PAAm.

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聚合物阻力降低的定量描述：聚丙烯酰胺分子量分布的影响

研究了聚丙烯酰胺（PAAm）分子量分布对两种流动几何形状下阻力降低的影响。在湍流管道流和旋转流中研究了不同重量平均分子量（Mw =5 × 105 至 1.8 × 107 g/mol）的商用 PAAm。对不同分子量分布的 PAAm 进行比较后发现，阻力的降低不仅是平均分子量的函数。与平均分子量相同但分布较窄的聚合物相比，分子量分布较宽的聚合物的阻力降低效果更好。由于聚合物在湍流中降解会导致分子量分布变窄，因此分布宽度的作用非常重要。采用多元线性回归将聚丙烯酰胺的重量分数与阻力降低联系起来。多元线性回归成功地用于描述湍流管道和旋转流中的阻力减小情况，表明阻力减小情况可从 PAAm 的分子量分布中定量得出。

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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.