Pressure-driven flow of wormlike micellar solutions in rectilinear microchannels

Cromer, Michael; Cook, L. Pamela; McKinley, Gareth H.

doi:10.1016/j.jnnfm.2010.11.007

Cited by 39 publications

(40 citation statements)

References 38 publications

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“…The nonlinear system of partial differential equations is solved by an adaptive domain decomposition spectral method. 27 For slow flow (i.e., for Wi below the critical value for linear instability), the concentration defect is damped and the steady state flow is the normal linear profile. We first consider two cases for Wi = 10, which is within the linear instability window for our chosen model parameters.…”

Section: -5mentioning

confidence: 99%

Shear banding in polymer solutions

et al. 2013

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The current theoretical belief is that the steady-state shear banding in viscoelastic liquids requires a non-monotonic constitutive relationship between shear stress and shear rate. Although existing rheological studies conclude that the constitutive equation for entangled polymers is monotonic, recent experimental evidence suggests shear banding can nevertheless occur in polymer solutions. In this work, we predict, for the first time, steady state shear banding with a realistic monotonic constitutive theory for polymeric liquids. The key is that a proper account must be taken of the coupling of polymer stress to polymer concentration. We also predict multiple steady states at some shear rates as seen experimentally, with shear banding if the flow is ramped quickly enough from rest, but homogeneous linear shear flow otherwise.

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Section: -5mentioning

confidence: 99%

Shear banding in polymer solutions

et al. 2013

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“…This issue has recently been considered in detail using numerical simulation [Cromer et al (2010); Nghe et al (2010)]. …”

Section: B Microscale Shear Flowsmentioning

confidence: 99%

“…At higher W i, however, the retardance along the channel centerline is finite indicating non-zero normal stress difference along the center of the channel. The increased contribution of elastic stresses even in regions of low shear rate near the channel centerline can be rationalized by the possibility of diffusion of elastic stresses due to the importance of non-local effects that have been documented in the microfluidic flows of other complex fluids [Masselon et al (2008)], and recently studied numerically [Cromer et al (2010)]. …”

Section: Background Corrected Birefringence Profilesmentioning

confidence: 99%

Spatially resolved quantitative rheo-optics of complex fluids in a microfluidic device

Ober¹,

Soulages²,

McKinley³

2011

Journal of Rheology

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In this study, we use micro-particle image velocimetry (µ-PIV) and adapt a commercial birefringence microscopy system for making full-field, quantitative measurements of flow-induced birefringence (FIB) for the purpose of microfluidic, opticalrheometry of two worm-like micellar solutions. In combination with conventional rheometric techniques, we use our microfluidic rheometer to study the properties of a shear-banding solution of cetylpyridinium chloride (CPyCl) with sodium salicylate (NaSal) and a nominally shear thinning system of cetyltrimethylammonium bromide (CTAB) with NaSal across many orders of magnitude of deformation rates (10 −2 ≤γ ≤ 10 4 s −1 ). We use µ-PIV to quantify the local kinematics and use the birefringence microscopy system in order to obtain high-resolution measurements of the changes in molecular orientation in the worm-like fluids under strong deformations in a microchannel. The FIB measurements reveal that the CPyCl system exhibits regions of localized, high optical anisotropy indicative of shear bands near the channel walls, whereas the birefringence in the shear-thinning CTAB system varies more smoothly across the width of the channel as the volumetric flow rate is increased. We compare the experimental results to the predictions of a simple constitutive model, and we document the break-down in the stress optical rule as the characteristic rate of deformation is increased.

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“…The non-local nature of the flow curve is caused by diffusion of more highly stressed micellar species to regions of lower stress, which can be significant because the small gap width in the microfluidic device (99.6 µm) results in large spatial gradients in the stress field. In this regime the flow is no longer truly determined by the local conditions, since the diffusion gives rise to stress boundary layers [52], which are typically on the order of δ ∼ 10 µm, thereby altering the resulting stress vs. shear rate relationship. This has been documented for this CPyCl/NaSal system by Ober et al [24].…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal dynamics of multiple shear-banding events for viscoelastic micellar fluids in cone-plate shearing flows

Casanellas¹,

Dimitriou²,

Ober³

et al. 2015

Journal of Non-Newtonian Fluid Mechanics

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We characterize the transient response of semi-dilute wormlike micellar solutions under an imposed steady shear flow in a cone-plate geometry. By combining conventional rheometry with 2-D Particle Image Velocimetry (PIV), we can simultaneously couple the temporal stress response with time-resolved velocimetric measurements. By imposing a well defined shear history protocol, consisting of a stepped shear flow sweep, we explore both the linear and nonlinear responses of two surfactant solutions: cetylpiridinium chloride (CPyCl) and sodium salicylate (NaSal) mixtures at concentrations of [66:40] mM and [100:60] mM, respectively. The transient stress signal of the more dilute solution relaxes to its equilibrium value very fast and the corresponding velocity profiles remain linear, even in the strongly shear-thinning regime. The more concentrated solution also exhibits linear velocity profiles at small shear rates. At large enough shear rates, typically larger than the inverse of the relaxation time of the fluid, the flow field reorganizes giving rise to strongly shear-banded velocity profiles. These are composed of an odd number of shear bands with lowshear-rate bands adjacent to both gap boundaries. In the non-linear regime long transients (much longer than the relaxation time of the fluid) are observed in the transient stress response before the fluid reaches a final, fully-developed state. The temporal evolution in the shear stress can be correlated with the spatiotemporal dynamics of the multiple shear-banded structure measured using RheoPIV. In particular our experiments show the onset of elastic instabilities in the flow which are characterized by the presence of multiple shear bands that evolve and rearrange in time resulting in a slow increase in the average torque acting on the rotating fixture.

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Pressure-driven flow of wormlike micellar solutions in rectilinear microchannels

Cited by 39 publications

References 38 publications

Shear banding in polymer solutions

Shear banding in polymer solutions

Spatially resolved quantitative rheo-optics of complex fluids in a microfluidic device

Spatiotemporal dynamics of multiple shear-banding events for viscoelastic micellar fluids in cone-plate shearing flows

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