Shear thickening of dilute suspensions of fractal silica aggregates

IF 2.7 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-04-23 DOI:10.1016/j.jnnfm.2024.105246

Sachidananda Barik , Pradip K. Bera , A.K. Sood , Sayantan Majumdar

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Abstract

The increase in viscosity under shear known as shear thickening (ST) is an inherent property of a wide variety of dense particulate suspensions. Recent studies indicate that ST systems formed by fractal particles are promising candidates for various practical applications. However, ST in fractal systems remains poorly explored. Here we experimentally study the ST behavior in suspensions of hydrophilic fumed silica (FS) particles in glycerol. Remarkably, unlike non-fractal systems, we observe a strong dependence of the onset stress for ST on the volume fraction of fractal objects and a reversible weakening of the ST response that depends strongly on the particle volume fraction as well as the properties of the FS system. Using in-situ boundary imaging, we map out the spatio-temporal flow properties during ST for different FS systems. We find that the fractal nature and structural properties like the internal branching of the particles can qualitatively explain the complex ST phase diagram of these systems.

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分形二氧化硅聚集体稀悬浮液的剪切增稠作用

在剪切作用下粘度的增加被称为剪切增稠（ST），是各种致密颗粒悬浮液的固有特性。最近的研究表明，由分形颗粒形成的 ST 系统有望在各种实际应用中发挥作用。然而，分形体系中的 ST 仍未得到充分探索。在此，我们通过实验研究了甘油中亲水性气相二氧化硅（FS）颗粒悬浮液的 ST 行为。值得注意的是，与非分形体系不同，我们观察到 ST 的起始应力与分形物体的体积分数有很大的关系，ST 响应的可逆减弱与颗粒的体积分数以及 FS 体系的特性有很大的关系。利用原位边界成像技术，我们绘制出了不同 FS 系统在 ST 过程中的时空流动特性图。我们发现，颗粒的分形性质和内部分支等结构特性可以定性地解释这些系统复杂的 ST 相图。

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.