Interplay between elastic instabilities and shear-banding: three categories of Taylor–Couette flows and beyond

Fardin, Marc-Antoine; Ober, Thomas J.; Grenard, Vincent; Divoux, Thibaut; Manneville, Sébastien; McKinley, Gareth H.; Lerouge, Sandra

doi:10.1039/c2sm26313k

Cited by 52 publications

(73 citation statements)

References 106 publications

(373 reference statements)

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“…The same procedure was performed for rates 10 s −1 , 12 s −1 , and 18 s −1 for the smooth wall and for Other values forγ a did not show any regular oscillation pattern and a wavelength extraction was not possible. In the case where a wavelength could be determined, it can be stated that the results are above the predictions (following Fardin et al (2012b)) by about a factor of two and that the wavelength is increasing for higher applied shear rates. The increase may be interpreted as linear, however, only four data points are available.…”

Section: Higher Dimensions: Vorticity Undulations and Temporal Fluctumentioning

confidence: 91%

“…The structure is reminiscent of Taylor-Couette vortices and has already been observed for over 20 years in the case of polymeric fluids (Larson et al 1990). A more thorough study (Fardin et al 2012b) found that the wavelength of the undulations scales linearly with the size of the high shear rate band, which is usually in the order of the gap width. In contrast, Feindel and Callaghan (2010) observed structures in vorticity direction in the order of centimeters.…”

Section: Higher Dimensions: Vorticity Undulations and Temporal Fluctumentioning

confidence: 92%

“…As mentioned, vorticity undulations for a variety of wormlike micellar systems similar to our sample have been studied in Fardin et al (2012b). Using the master curve shown in Fig.…”

Section: Higher Dimensions: Vorticity Undulations and Temporal Fluctumentioning

confidence: 99%

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Anomalous shear banding revisited with Rheo-NMR and Rheo-USV

et al. 2015

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A combined two-dimensional Rheo-NMR velocimetry and two-dimensional Rheo-USV approach is used to further elucidate the flow of a wormlike micellar solution in cylindrical Couette geometries. Recent experimental enhancements for both methods enable a more detailed description of the flow dynamics than available in the past. This enabled us to revisit and investigate shear banded flow utilizing improved spatial and temporal resolution, clearly confirming a departure from a simple lever rule for the micellar solution under study. Both experimental techniques observe different shear rates in the high shear rate band accompanied by a varying position of the interface between bands for different applied shear rates. Furthermore, spatially and temporally resolved velocimetry reveals various flow instabilities. Ultrasound measurements show vorticity undulations with wavelengths that scale linearly with the size of the high shear rate band. For high enough shear rates, the occurrence of turbulent bursts is detected in the USV case. However, no direct evidence of these bursts is found in the NMRmeasurements for equivalent shear rates, which we attribute so far to differences in the design of the shearing geometries.

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Section: Higher Dimensions: Vorticity Undulations and Temporal Fluctumentioning

confidence: 91%

Section: Higher Dimensions: Vorticity Undulations and Temporal Fluctumentioning

confidence: 92%

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Anomalous shear banding revisited with Rheo-NMR and Rheo-USV

et al. 2015

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“…While inertia is at the heart of flow instabilities in simple fluids, non-Newtonian fluids, such as polymer or self-assembled surfactant solutions, may display instabilities at vanishingly small Reynolds numbers due to elasticity [7,8] or due to a strong coupling between the flow and the fluid microstructure [9]. A typical example is provided by wormlike micellar solutions where shear-induced alignment associated with high viscoelasticity leads to shear-banded flows that transition to elastic turbulence at high Weissenberg numbers [10].…”

Section: Introductionmentioning

confidence: 99%

Uncovering Instabilities in the Spatiotemporal Dynamics of a Shear-Thickening Cornstarch Suspension

2018

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Recent theories predict that discontinuous shear thickening (DST) involves an instability, the nature of which remains elusive. Here, we explore unsteady dynamics in a dense cornstarch suspension by coupling long rheological measurements under constant shear stresses to ultrasound imaging. We demonstrate that unsteadiness in DST results from localized bands that travel along the vorticity direction with a specific signature on the global shear rate response. These propagating events coexist with quiescent phases for stresses slightly above DST onset, resulting in intermittent, turbulentlike dynamics. Deeper into DST, events proliferate, leading to simpler, Gaussian dynamics. We interpret our results in terms of unstable vorticity bands as inferred from recent model and numerical simulations.

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“…They expanded the parameter regime studied by systematically tuning the surfactant concentration of the solutions [33], and elucidated the interplay between elastic instabilities and shear-banding. More recently, they tested an even more diluted non-shear-banding wormlike micellar solution (CTAB/NaNO 3 [0.1:0.3] M) [34].…”

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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Interplay between elastic instabilities and shear-banding: three categories of Taylor–Couette flows and beyond

Cited by 52 publications

References 106 publications

Anomalous shear banding revisited with Rheo-NMR and Rheo-USV

Anomalous shear banding revisited with Rheo-NMR and Rheo-USV

Uncovering Instabilities in the Spatiotemporal Dynamics of a Shear-Thickening Cornstarch Suspension

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

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