How do soft particle glasses yield and flow near solid surfaces?

Seth, Jyoti R.; Locatelli-Champagne, Clémentine; Monti, Fabrice; Bonnecaze, Roger T.; Cloître, Michel

doi:10.1039/c1sm06074k

Cited by 102 publications

(162 citation statements)

References 42 publications

(74 reference statements)

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“…The collapse of the data shows that the effect of concentration is a function of τ y and G 0 , in agreement with data for colloidal scale microgels and emulsions (Seth et al, 2012).…”

Section: Influence Of Suspension Concentration and Particle Sizesupporting

confidence: 75%

“…Elastohydrodynamic lubrication theory (Meeker et al, 2004a, Meeker et al, 2004b, Seth et al, 2008, Seth et al, 2012 has been applied to both sets of particles for an accurate prediction of the slip velocity. This calculation clearly shows the dependence of slip velocity on G p .…”

Section: Discussionmentioning

confidence: 99%

“…No clear difference has previously been shown between φ j and φ m , as published work commonly uses 'free fitting' to determine the maximum packing fraction, and most studies utilise colloidal-scale microgels or emulsions which each have limitations (Mason et al, 1997, Senff andRichtering, 2000). The limitation with colloidal-scale synthetic polymer microgels is that their phase volume is difficult to define and alters with concentrationosmotically de-swelling at high concentration (Seth et al, 2012). The difficulty with concentrated emulsions lies in accurately determining: phase volume; droplet interactions;…”

Section: Viscoelastic Liquid-like Behaviour From Random Close Packingmentioning

confidence: 99%

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Rheology of soft particle suspensions

Shewan¹

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The purpose of this work is to investigate the effect of particle elasticity on suspension rheology and flow. Non-colloidal (~ 10 µm) spherical agarose microgels suspended in water are used as a model system. The advantage of these microgels is that they are manufactured to a specific elastic modulus, ranging from 8 to 300 kPa, determined from the modulus of an agarose gel disk. This is in contrast to routinely studied colloidal microgels where the particle modulus cannot be established. Colloidal microgel modulus and specific volume are variable as they are responsive to suspension conditions (such as, pH, temperature and osmotic pressure). Using experimental rheology, an investigation was carried out into the liquid and solid-like behaviour of agarose microgel suspensions. Suspension concentration regimes from dilute to densely packed were investigated to show explicitly the effect of particle modulus on rheology, which becomes increasingly more significant with increasing phase volume. In addition, particle modulus is shown to influence two shear flow characteristics -slip and shear thickening.To interpret suspension viscosity as a function of phase volume the model, developed by Maron and Pierce (1956) and popularised by Quemada (1977) (MPQ model), is applied. This model is based on a scaling relation of the pair distribution function and predicts the critical phase volume at which the viscosity tends to infinity, corresponding to when spherical particles are randomly close packed (φ rcp ).Commonly, it is used empirically by free fitting of experimental data to obtain the critical phase volume. In this work, a method has been developed to use the MPQ model in accordance with its theoretical basis by independently predicting φ rcp from the particle size distribution. It is shown that this theoretical form of the MPQ model, with no adjustable parameters, results in an accurate prediction (within experimental uncertainty, ± 5 %) of the viscosity-phase volume relationship for hard spheres. In addition, alterations in suspension microstructure (for example, through particle aggregation) or rheological artefacts (such as, particle migration) are readily identified by plotting the MPQ model in a linear form.In contrast to hard spheres, the phase volume of agarose microgels is difficult to define accurately. The approach typically used in literature, and used here, is to iii define the specific volume from dilute suspension viscosity. This approach can be corroborated using the theoretical viscosity-phase volume model validated with hard sphere suspensions. The specific volume of agarose microgels is easily defined at φ rcp using the particle size distribution. From this approach it is discovered that, in the viscous regime, below φ rcp , particle elasticity does not explicitly affect suspension viscosity. However, it is shown that particle elasticity has an indirect effect on viscosity at phase volumes between ~ 0.4 and φ rcp due to limited re-swelling during microgel preparation procedures.When microgels c...

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“…The collapse of the data shows that the effect of concentration is a function of τ y and G 0 , in agreement with data for colloidal scale microgels and emulsions (Seth et al, 2012).…”

Section: Influence Of Suspension Concentration and Particle Sizesupporting

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Section: Viscoelastic Liquid-like Behaviour From Random Close Packingmentioning

confidence: 99%

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Rheology of soft particle suspensions

Shewan¹

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“…Albeit less visible, this effect should also appear with walls characterised by a smaller roughness, whereby rough walls in the presence of slip act as sources of mechanical noise and cause deviations from bulk rheology in their vicinity. This tentative scenario has the potential to explain why deviations may, or may not, be observed in the vicinity of rough surfaces: for instance, Goyon et al 44 and Ovarlez et al 53 , as well as Seth and co-workers 73 , have reported that the local flow curves obtained Diverse methods are available for roughening a surface, such as sandblasting, covering it with sandpaper, or coating it with particles.…”

Section: Physical Effect Of Rough Wallsmentioning

confidence: 99%

“…39,40,[44][45][46]52,58,73 ). In this approach, the fluidity at the wall is needed as an input parameter, whose precise value turns out to be determinant.…”

Section: Fictitious Plastic Events Along the Wall As Mechanical Noisementioning

confidence: 99%

A mesoscopic model for the rheology of soft amorphous solids, with application to microchannel flows

Nicolas

Barrat

2013

Faraday Discuss.

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We study a mesoscopic model for the flow of amorphous solids. The model is based on the key features identified at the microscopic level, namely periods of elastic deformation interspersed with localised rearrangements of particles that induce long-range elastic deformation. These long-range deformations are derived following a continuum mechanics approach, in the presence of solid boundaries, and are included in full in the model. Indeed, they mediate spatial cooperativity in the flow, whereby a localised rearrangement may lead a distant region to yield. In particular, we simulate a channel flow and find manifestations of spatial cooperativity that are consistent with published experimental observations for concentrated emulsions in microchannels. Two categories of effects are distinguished. On the one hand, the coupling of regions subject to different shear rates, for instance,leads to finite shear rate fluctuations in the seemingly unsheared "plug" in the centre of the channel. On the other hand, there is convincing experimental evidence of a specific rheology near rough walls. We discuss diverse possible physical origins for this effect, and we suggest that it may be associated with the bumps of particles into surface asperities as they slide along the wall.

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Boost and Contraction of Flow by Herringbone Surface Design on the Microfluidic Channel Wall

Filippi¹,

Derzsi

Nalin

et al. 2023

Adv Materials Technologies

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The handling of yield-stress fluids typically involves a jammed-to-flow transition that is pivotal for many injection and transport technologies on different scales, such as additive manufacturing, injection molding, food rheology, and oil transport. For all of these applications, it is crucial to be able to tune the fluidization under constant load. The pressure-driven flow of emulsions is reported within a microfluidic channel, one wall of which is patterned by a herringbone-riblet roughness comprising a regular array of V-shaped grooves. With respect to the pressure gradient, this pattern displays a convergent (divergent) orientation that provides a forward (backward) direction. At the tip of the herringbone pattern, the forward and backward flows are almost identical for a viscous Newtonian fluid and a diluted emulsion, whereas a surprising flow boost in the forward direction is observed as the emulsion approaches a jammed state. The flow boost is more effective at small herringbone angles and low pressure loads. 3D velocity profiles along the channel cross-section unravel unexpected heterogeneous stress, band-like distributed, with evidence of nonlocal correlations.

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How do soft particle glasses yield and flow near solid surfaces?

Cited by 102 publications

References 42 publications

Rheology of soft particle suspensions

Rheology of soft particle suspensions

A mesoscopic model for the rheology of soft amorphous solids, with application to microchannel flows

Boost and Contraction of Flow by Herringbone Surface Design on the Microfluidic Channel Wall

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