Studies of the viscosity and sedimentation of suspensions Part 1. - The viscosity of suspension of spherical particles

Ward, Stacey G.; Whitmore, R L

doi:10.1088/0508-3443/1/11/303

Cited by 77 publications

(19 citation statements)

References 21 publications

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“…This is far less than the volume fractions of up to u = 0.30-0.50 used in experiments such as the classical ones designed to measure the viscosity of suspensions where the particle-to-tube diameter ratio was at most 0.007 (Ward and Whitmore 1950) and 0.07 (Vand 1948). The purpose of the current work is to report the occurrence of flow blockages over a range of " d p =D from 0.2 to 0.5 and u < 0.06, and to propose a possible mechanism for the observed blockages.…”

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confidence: 87%

On flow-blocking particle structures in microtubes

Sharp

Adrian

2005

Microfluid Nanofluid

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Given their small size, microchannels are susceptible to being blocked by small amounts of solid matter. The lifetime of certain microfluidic devices depends on their ability to maintain flow without interruption, and certain microfluidic applications require devices that include the transport of either liquids that may contain impurities or liquids that intentionally contain particles. Under the conditions studied in the present experiments, flow-stopping blockages were observed for the flow of liquids with the surprisingly low volume concentrations of u = 0.005-0.056 of polystyrene particles (d p of the order of tens of microns) through circular microtubes with diameters (D) of the order of 100 lm. The quantity of interest is the occurrence of a flow-stopping blockage in the flow of a suspension of hard spheres, over the range of " d p =D from 0.2 to 0.5 and u < 0.06. The percentage of runs for which a blockage did or did not occur versus nominal d p /D is presented. Given that higher concentrations of particles have been used in many previous studies of suspension flows, the occurrence of blockages at these concentrations was initially unexpected. Based upon the data and the parameters varied in the current study, the blockages are more likely to occur when the nominal particle-totube diameter ratios are approximately 0.3-0.4.

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confidence: 87%

On flow-blocking particle structures in microtubes

Sharp

Adrian

2005

Microfluid Nanofluid

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“…Ward and Whitmore [65] experimented on microsphere-aqueous suspension in a bid to verify the Einstein equation. They concluded that the intrinsic viscosity given by Einstein is a function of PSD ratio, which is approximately 4.0 for an infinitely diluted suspension with PSD ratio 1:1 and approximately 1.9 for PSD ratio exceeding 3:1.…”

Section: Classical Theoretical Modelsmentioning

confidence: 99%

The Viscosity of Nanofluids: A Review of the Theoretical, Empirical, and Numerical Models

Meyer

Adio

Sharifpur

et al. 2015

Heat Transfer Engineering

201

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The enhanced thermal characteristics of nanofluids have made it one of the fastest-growing research areas in the last decade. Numerous researches have shown the merits of nanofluids in heat transfer equipment. However, one of the problems is the increase in viscosity due to the suspension of nanoparticles. This viscosity increase is not desirable in the industry, especially when it involves flow, such as in heat exchanger or micro-channel applications INTRODUCTIONColloidal suspension dates back to Maxwell's study in 1873 [1]. Though the idea behind his study was vivid, the imposed problems were too enormous for profitable engineering solutions [2]. In 1995, Choi [3] came up with a pioneering idea based on Maxwell's study and suspended ultrafine particles (nanoparticles) in conventional heat transfer fluids. His invention has opened up a myriad of opportunities in research and development. Nanofluids descriptively are colloidal suspensions containing metallic (Ag, Au, Al, Cu, Ni, etc.), non-metallic (single-and multi-wall carbon nanotube (SWCNT and MWCNT), Si, Graphene, etc.), metallic oxide (Al2O3, CuO, NiO2,TiO2, etc.) and oxides of non-metals (SiO2, SiC, MgO, CaCO3, etc.) nanoparticles suspended in conventional heat transfer fluids such as water, engine oil, ethylene glycol, transformer oil, gear oil or mixture of two or more heat transfer fluids [2,3]. When compared with previous microparticle suspensions in conventional heat transfer fluids, it is a special type of fluid with numerous applications potentials because of its enhanced thermal conductivity, stability and homogeneity [3,4]. Microscale particles in suspensions lead to abrasion, clogging of flow paths, pressure drop and high pumping power requirements, therefore, its sustainability was impossible. Besides, nanofluids can reduce the pumping power in engineering equipment significantly and do not pose the problem of clogging and abrasion of equipment flow paths [5][6][7][8]. Therefore, the design and engineering of physical systems are now being tailored towards using nanofluid as working fluid.The impact of colloidal suspension cuts across the fields of science, biological science, medical, pharmaceutical and engineering. In the context of sustainable energy development and thermal management, nanofluids are becoming more and more significant as the need for efficient thermal management is of paramount importance. Moreover, the level of miniaturisation of devices today as technology advances is overwhelming. Devices such as microprocessors, microelectromechanical systems (MEMS), nanoelectromechanical systems (NEMS), microchannels and lab-on-chips come with high-density heat flux that needs quick heat removal for 3 efficient performance, stability and durability, which, from all indications, could be provided by nanofluids for now [9][10][11][12]. The following are also emerging areas of applications of nanoparticles and nanofluids: (i) they could be useful in medicine in the targeted treatment of malignant cells without damaging healthy tis...

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“…The influence of the particles shape on the bulk viscosity has been studied for low Re number suspensions. [30][31][32] These studies showed that the more the shape of the particle deviated from that of a sphere, the greater was the bulk viscosity. Moreover, aspherical particles demonstrate increased ordering near the walls (an effect which is more pronounced for the smooth walls).…”

Section: -7mentioning

confidence: 99%

Rheological measurements of large particles in high shear rate flows

et al. 2012

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How to impose stick boundary conditions in coarse-grained hydrodynamics of Brownian colloids and semiflexible fiber rheology J. Chem. Phys. 136, 064901 (2012) This paper presents experimental measurements of the rheological behavior of liquid-solid mixtures at moderate Stokes and Reynolds numbers. The experiments were performed in a coaxial rheometer that was designed to minimize the effects of secondary flows. By changing the shear rate, particle size, and liquid viscosity, the Reynolds numbers based on shear rate and particle diameter ranged from 20 to 800 (Stokes numbers from 3 to 90), which is higher than examined in earlier rheometric studies. Prior studies have suggested that as the shear rate is increased, particleparticle collisions also increase resulting in a shear stress that depends non-linearly on the shear rate. However, over the range of conditions that were examined in this study, the shear stress showed a linear dependence on the shear rate. Hence, the effective relative viscosity is independent of the Reynolds and Stokes numbers and a nonlinear function of the solid fraction. The present work also includes a series of roughwall experiments that show the relative effective viscosity is also independent of the shear rate and larger than in the smooth wall experiments. In addition, measurements were made of the near-wall particle velocities, which demonstrate the presence of slip at the wall for the smooth-walled experiments. The depletion layer thickness, a region next to the walls where the solid fraction decreases, was calculated based on these measurements. The relative effective viscosities in the current work are larger than found in low-Reynolds number suspension studies but are comparable with a few granular suspension studies from which the relative effective viscosities can be inferred.

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Studies of the viscosity and sedimentation of suspensions Part 1. - The viscosity of suspension of spherical particles

Cited by 77 publications

References 21 publications

On flow-blocking particle structures in microtubes

On flow-blocking particle structures in microtubes

The Viscosity of Nanofluids: A Review of the Theoretical, Empirical, and Numerical Models

Rheological measurements of large particles in high shear rate flows

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