Influence of surface properties on the flow of a yield stress fluid around spheres

Ahonguio, Fiacre; Jossic, Laurent; Magnin, Albert

doi:10.1016/j.jnnfm.2014.03.002

Cited by 43 publications

(46 citation statements)

References 33 publications

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“…Gueslin et al [26] provided an in-depth study of the velocity field but this concerned a thixotropic material for which there can be a further, and maybe dramatic, impact of the intense shear rate close to the object surface. Finally some works [27,28] (for spheres) and [24] (for cylinders) provided new detailed data concerning the velocity field around an object moving through a yield stress fluid. They found a significant discrepancy of the velocity field with that computed from simulations.…”

Section: Introductionmentioning

confidence: 99%

Flow characteristics around a plate withdrawn from a bath of yield stress fluid

Maillard

Boujlel

Coussot

2015

Journal of Non-Newtonian Fluid Mechanics

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International audienceDip-coating is a process widely used in industry to coat a fluid on a solid substrate. The general charac-teristics of dip-coating for simple liquids (Newtonian) are well known but a lot of applications involve complex fluids. Here we focus on the case of a solid plate coated with a yield stress fluid through the immersion followed by the withdrawal of a plate from a bath of such fluid. We carried out a precise anal-ysis of the force applied to the plate during its withdrawal from the bath, and determined the velocity field developed around the plate in the fluid bath with the PIV technique. It appears that, inside the bath, after a transient regime during the plate withdrawal, a linear force regime is set up, which is associated with a stationary uniform flow (liquid region) settled along the plate while the rest of the material is in its solid regime. We show that the thickness of this liquid region increases slowly with the plate velocity and its value is almost the same for immersion and withdrawal, and independent of a possible period of rest preceding plate motion. Finally we show that the thickness of the liquid region is related to the force in the linear regime

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Section: Introductionmentioning

confidence: 99%

Flow characteristics around a plate withdrawn from a bath of yield stress fluid

Maillard

Boujlel

Coussot

2015

Journal of Non-Newtonian Fluid Mechanics

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“…However, they are difficult to test without meaningful measurements of components of the stress tensor other than the shear stress; normal stress measurements are in fact standard in polymer rheology to test constitutive relations. Not only do very few measurements of the normal stress in yield-stress fluids exist, but those that exist do not provide a coherent picture: positive N1 [11] [12] [13] [14] has been reported for some systems, whereas negative N1 has been reported for others [15] [16]. The main issue that has to be dealt with is that their measurement is challenging because the flow is often heterogeneous [17] [18], and the systems may have residual stresses and uncontrolled trapped strains [19], underlining the importance of experimental protocols [14].…”

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confidence: 99%

The yield normal stress

Cagny

Fazilati

Habibi

et al. 2019

Journal of Rheology

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Normal stresses in complex fluids lead to new flow phenomena because they can be comparable to or even larger than the shear stress itself. In addition, they are of paramount importance for formulating and testing constitutive equations for predicting non-viscometric flow behavior. Very little attention has so far been paid to the normal stresses of yield stress fluids, which are difficult to measure. We report the first systematic study of the first and second normal stress differences, N1 (>0) and N2 (<0), in both continuous and oscillatory shear of three model yield stress fluids. We show that both normal stress differences are quadratic functions of the shear stress both above and below the shear yield stress, leading to the existence of a yield normal stress.

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“…The magnitude of normal yield stress is of the same order of magnitude as the yield stress of the shear stress. For Carbopol gels used in the present study, Ahonguio et al measured for the first normal stress (in Pa) N 1 = 93.5 + 119

\overset{normalγ}{true}

. 0.44…”

Section: Comparison Between Numerical and Experimentalmentioning

confidence: 68%

“…Ahonguio et al studied experimentally the flow of a yield stress fluid around spheres with respect to surface roughness. Drag coefficient expression given is described below at low Reynolds numbers:

{Cd}^{*} = 18.56 + 35.68 . {Od}^{- 0.77}

…”

Section: Theorymentioning

confidence: 99%

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Flow of a Newtonian fluid and a yield stress fluid around a plate inclined at 45° in interaction with a wall

2019

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This experimental and numerical study focuses on the determination of drag and lifts forces acting on inclined plate at 45° placed near a wall in a uniform flow of Newtonian and yield stress fluid. The inertia of the fluid is considered negligible. The influences of yield stress, shear thinning, and the distance between the plate and the wall were examined precisely. It is shown that the drag and lift coefficients decrease as the Oldroyd number increases and increase as the gap decreases. The unyielded zones around the plate were also determined. Their surfaces increase with the Oldroyd number. When the yield stress is low, the decrease of the shear thinning index n tends to decrease these unyielded zones. For the experimental part, a Carbopol gel was used as a fluid model. Experimental measurements were compared with numerical and published results, particularly in the plasticity context developed for soil mechanics. Differences are discussed in terms of the influence of elasticity and plasticity.

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Influence of surface properties on the flow of a yield stress fluid around spheres

Cited by 43 publications

References 33 publications

Flow characteristics around a plate withdrawn from a bath of yield stress fluid

Flow characteristics around a plate withdrawn from a bath of yield stress fluid

The yield normal stress

Flow of a Newtonian fluid and a yield stress fluid around a plate inclined at 45° in interaction with a wall

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