Viscoplastic flow development in tubes and channels with wall slip

Philippou, Maria; Kountouriotis, Zacharias; Georgiou, Georgios C.

doi:10.1016/j.jnnfm.2016.04.008

Cited by 17 publications

(4 citation statements)

References 20 publications

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“…Thus the slip behavior of materials needs to be characterized and used as appropriate boundary conditions in the mathematical modeling and simulation of complex processes like capillary flows, slit flows and extrusion flows (Lawal and Kalyon 1994a, b;Kalyon et al 1999;Kalyon 2005). The existence of slip has also important ramifications on the development of flow instabilities during the extrusion of highly filled polymeric suspensions (Denn 2001;Birinci and Kalyon 2006;Tang and Kalyon 2008), the spreading of yield stress fluids (Luu and Forterre 2009;Saïdi et al 2011, Jalaal et al 2015, and the establishment of steady conditions during start up flows or cessation flows of yield stress materials (Damaniou et al 2014;Philippou et al 2016). Far from being just a nuisance, slip is thus fundamental to the way that high solid dispersions respond and behave.…”

Section: Introductionmentioning

confidence: 99%

A review on wall slip in high solid dispersions

2017

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High solid dispersions are soft materials made of colloidal or non colloidal particles dispersed at high volume fractions in a liquid matrix. They include hard sphere glasses, colloidal pastes, concentrated emulsions, foams, and vesicles. These materials are prone to exhibit different kinds of flow heterogeneities: shear-banding, wall slip, and fracture. While wall slip is often considered as a nuisance by experimentalists, it appears to be a fundamental component to the way that high solid dispersions respond to mechanical deformation. Moreover the ability of soft materials to slip onto surfaces allows them to move readily and efficiently in many natural phenomena and industrial processes. This review surveys recent developments and current research in the field. Topics like wall slip detection and control, microscopic modeling for rigid and soft particles materials, and the relation between wall slip and other flow heterogeneities are discussed. We also identify important open issues for future research.

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Section: Introductionmentioning

confidence: 99%

A review on wall slip in high solid dispersions

2017

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“…[12][13][14] The occurrence of slip has also important consequences on the development of flow instabilities during the extrusion of highly filled polymeric suspensions, 15,16 the spreading of yield stress fluids, 17,18 and the establishment of steady conditions during start up flows or cessation flows of yield stress materials. 19,20 Hence the occurrence of slip for complex materials must be considered as an important and intrinsic feature of its flow and deformation behaviour. Mooney introduced a method to analyze slip and measure slip velocities in capillary and rotational rheometry; these rely on multiple measurements performed with the same capillary length over diameter ratios but different diameters or different parallel plate gap sizes, respectively.…”

Section: Introductionmentioning

confidence: 99%

Particle–wall tribology of slippery hydrogel particle suspensions

2017

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Slip is an important phenomenon that occurs during the flow of yield stress fluids like soft materials and pastes. Densely packed suspensions of hydrogel microparticles are used to show that slip is governed by the tribological interactions occurring between the samples and shearing surfaces. Both attractive/repulsive interactions between the dispersed particles and surface, as well as the viscoelasticity of the suspension, are found to play key roles in slip occurring within rheometric flows. We specifically discover that for two completely different sets of microgels, the sliding stress at which slip occurs scales with both the modulus of the particles and the bulk suspension modulus. This suggests that hysteresis losses within the viscoelastic particles contribute to friction forces and thus slip at the particle-surface tribo-contact. It is also found that slip during large amplitude oscillatory shear and steady shear flows share the same generic features.

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“…In the present study, the objective is to systematically address the effect of slip on yield-stress fluid flows and its consequences on the yield limit; not only by conducting numerical simulations, but also by forming a theoretical framework for analysing this type of problem. Although some attempts have been made to solve simple rheometric flows in previous years (Philippou, Kountouriotis & Georgiou 2016; Panaseti & Georgiou 2017; Damianou, Panaseti & Georgiou 2019), still the lack of generic numerical implementation frameworks (especially non-regularized methods) and the absence of adequate theoretical frameworks to attack sliding yield-stress fluid flows are discernible. Hence, in what follows, we aim to partially fill this gap in the literature.…”

Section: Introductionmentioning

confidence: 99%