Oscillating Viscosity in a Lyotropic Lamellar Phase under Shear Flow

Wunenburger, Anne-Sophie; Colin, Annie; Leng, Jacques; Arnéodo, A.; Roux, D.

doi:10.1103/physrevlett.86.1374

Cited by 93 publications

(102 citation statements)

References 21 publications

(30 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The first type of unstable temporal behavior comprises sustained, periodic oscillations of the shear rate at constant imposed shear stress, or vice-versa: this has been observed for surfactant solutions either in wormlike micellar phases [10,11,12,13,14] or lamellar phases [15,16,17,18], as well as in polymer solutions [19] and concentrated colloids [20]. The second type of unsteady behavior is more complex, with erratic temporal responses of either the shear rate or shear stress.…”

Section: Introductionmentioning

confidence: 99%

“…Candidates for slow structural modes include the mean length or the local gel fraction in worm-like micelles; local composition variables (e.g., colloidal volume fraction); and 'fluidity' parameters reflecting, e.g., a local bonding state [31,37]. An involvement of slowly evolving structure has been shown in many experimental cases [10,11,12,13,14,15,16,17,18,19].…”

Section: The Modelmentioning

confidence: 99%

“…The methods used include birefringence imaging [11,19], light scattering [15,16] and spatially resolved NMR [24]. Many (but not quite all) instances of structural instability occur in shear-stress or shear-rate ranges close to non-equilibrium transitions between distinct phases or textures in the fluid, for example the transition from isotropic to flowaligned-nematic structures in worm-like micelles [24], or the disordered-to-layered packing transition in multilamellar onions [15,16,17,25]. (There may also be underlying transitions from a flowing to a jammed state in colloids [26], and from isotropic to string-like structures in polymer solutions [19].)…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Minimal model for chaotic shear banding in shear thickening fluids

Aradian

Cates

2006

Phys. Rev. E

View full text Add to dashboard Cite

We present a minimal model for spatiotemporal oscillation and rheochaos in shear-thickening complex fluids at zero Reynolds number. In the model, a tendency towards inhomogeneous flows in the form of shear bands combines with a slow structural dynamics, modelled by delayed stress relaxation. Using Fourier-space numerics, we study the nonequilibrium 'phase diagram' of the fluid as a function of a steady mean (spatially averaged) stress, and of the relaxation time for structural relaxation. We find several distinct regions of periodic behavior (oscillating bands, travelling bands, and more complex oscillations) and also regions of spatiotemporal rheochaos. A low-dimensional truncation of the model retains the important physical features of the full model (including rheochaos) despite the suppression of sharply defined interfaces between shear bands. Our model maps onto the FitzHugh-Nagumo model for neural network dynamics, with an unusual form of long-range coupling.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: The Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Minimal model for chaotic shear banding in shear thickening fluids

Aradian

Cates

2006

Phys. Rev. E

View full text Add to dashboard Cite

show abstract

“…This leads to a separation into bands of differing shear rate that coexist at a common shear stress [2,3]. Although most studies have assumed a flat interface between the bands and (with a few exceptions [4]) predicted a timeindependent banded state, an accumulating body of data has demonstrated that the average shear stress, and the banding interface, can fluctuate [5,6,7,8,9,10,11,19]. An important question is then whether these fluctuations resemble small amplitude capillary waves stabilised by surface tension, or whether they arise from an underlying instability, stabilised at large amplitude by nonlinearities.…”

mentioning

confidence: 99%

Nonlinear Dynamics of an Interface between Shear Bands

Fielding

Olmsted

2006

Phys. Rev. Lett.

View full text Add to dashboard Cite

We study numerically the nonlinear dynamics of a shear banding interface in two dimensional planar shear flow, within the non-local Johnson Segalman model. Consistent with a recent linear stability analysis, we find that an initially flat interface is unstable with respect to small undulations for sufficiently small ratio of the interfacial width ℓ to cell length Lx. The instability saturates in finite amplitude interfacial fluctuations. For decreasing ℓ/Lx these undergo a non equilibrium transition from simple travelling interfacial waves with constant average wall stress, to periodically rippling waves with a periodic stress response. When multiple shear bands are present we find erratic interfacial dynamics and a stress response suggesting low dimensional chaos.PACS numbers: 47.50.+d, 47.20.-k, 36.20.-r. Complex fluids such as polymers, liquid crystals and surfactant solutions have mesoscopic structure that is readily perturbed by flow [1]. For example, wormlike surfactant micelles with lengths of the order of microns can be induced to stretch, disentangle and entangle, and break or increase in length. Their mechanical response is therefore highly non-Newtonian, with shear flows inducing normal stresses (e.g. σ xx − σ yy ), and with the shear stress σ xy being a nonlinear function of applied shear ratė γ. Recent work on such fluids has led to a fairly consistent picture of "shear banding": coexistence in shear flow of viscously thicker (nascent) and thinner (flow-induced) bands of material flowing at different local shear rates, for an overall average imposed shear rate. This phenomenon can be described by constitutive models for which the shear stress is a non-monotonic function of shear rate for homogeneous flow. This leads to a separation into bands of differing shear rate that coexist at a common shear stress [2,3]. Although most studies have assumed a flat interface between the bands and (with a few exceptions [4]) predicted a timeindependent banded state, an accumulating body of data has demonstrated that the average shear stress, and the banding interface, can fluctuate [5,6,7,8,9,10,11,19]. An important question is then whether these fluctuations resemble small amplitude capillary waves stabilised by surface tension, or whether they arise from an underlying instability, stabilised at large amplitude by nonlinearities. In this Letter we give strong evidence supporting the latter scenario, via the first theoretical study of the nonlinear dynamics of a shear banding interface.The model -The generalised Navier Stokes equation for a viscoelastic material in a Newtonian solvent of viscosity η and density ρ is:where v(r) is the velocity field. The pressure P is determined by incompressibility, ∇ · v = 0. The viscoelastic stress Σ(r) evolves according to the non-local ("diffusive") Johnson Segalman (DJS) model [12,13] (with plateau modulus G and relaxation time τ . D and Ω are the symmetric and antisymmetric parts of the velocity gradient tensor, (∇v) αβ ≡ ∂ α v β . For a = 1 and ℓ = 0 this model reduces t...

show abstract

“…In some extreme cases, one not only observes bands of different structures and flow properties, but also large temporal fluctuations of the global sample viscosity [10,11,12]. This last behaviour, recently coined "rheochaos" [13], is observed in the vicinity of the shearinduced transitions described above.…”

Section: Examples Of Inhomogeneous Flows In Complex Fluidsmentioning

confidence: 91%

An optical fiber based interferometer to measure velocity profiles in sheared complex fluids

et al. 2003

Self Cite

View full text Add to dashboard Cite

Abstract. We describe an optical fiber based interferometer to measure velocity profiles in sheared complex fluids using Dynamic Light Scattering (DLS). After a review of the theoretical problem of DLS under shear, a detailed description of the setup is given. We outline the various experimental difficulties induced by refraction when using a Couette cell. We also show that homodyne DLS is not well suited to measure quantitative velocity profiles in narrow-gap Couette geometries. On the other hand, the heterodyne technique allows us to determine the velocity field inside the gap of a Couette cell. All the technical features of the setup, namely its spatial resolution (≈ 50-100 µm) and its temporal resolution (≈ 1 s per point, ≈ 1 min per profile) are discussed, as well as the calibration procedure with a Newtonian fluid. As briefly shown on oil-in-water emulsions, such a setup permits one to record both velocity profiles and rheological data simultaneously.

show abstract

Oscillating Viscosity in a Lyotropic Lamellar Phase under Shear Flow

Cited by 93 publications

References 21 publications

Minimal model for chaotic shear banding in shear thickening fluids

Minimal model for chaotic shear banding in shear thickening fluids

Nonlinear Dynamics of an Interface between Shear Bands

An optical fiber based interferometer to measure velocity profiles in sheared complex fluids

Contact Info

Product

Resources

About