Two step micro-rheological behavior in a viscoelastic fluid

Abstract

We perform micro-rheological experiments with a colloidal bead driven through a viscoelastic worm-like micellar fluid and observe two distinctive shear thinning regimes, each of them displaying a Newtonian-like plateau. The shear thinning behavior at larger velocities is in qualitative agreement with macroscopic rheological experiments. The second process, observed at Weissenberg numbers as small as a few percent, appears to have no analog in macro rheological findings. A simple model introduced earlier captures the observed behavior, and implies that the two shear thinning processes correspond to two different length scales in the fluid. This model also reproduces oscillations which have been observed in this system previously. While the system under macro-shear seems to be near equilibrium for shear rates in the regime of the intermediate Newtonian-like plateau, the one under micro-shear is thus still far from it. The analysis suggests the existence of a length scale of a few micrometres, the nature of which remains elusive.

arXiv comment7 pages, 5 figures

References in corpus (20)

• Stochastic thermodynamics, fluctuation theorems, and molecular machines
• Three-dimensional imaging of colloidal glasses under steady shear
• Schematic models for dynamic yielding of sheared colloidal glasses
• Active and Nonlinear Microrheology in Dense Colloidal Suspensions
• Shear zones and wall slip in the capillary flow of concentrated colloidal suspensions
• From Equilibrium to Steady State: The Transient Dynamics of Colloidal Liquids under Shear
• Oscillating Modes of Driven Colloids in Overdamped Systems
• Geometry-induced superdiffusion in driven crowded systems
• Transient dynamics of a colloidal particle driven through a viscoelastic fluid
• Generalized Langevin equation and fluctuation-dissipation theorem for particle-bath systems in external oscillating fields
• A dynamic density functional theory for particles in a flowing solvent
• Dynamic density functional study of a driven colloidal particle in polymer solutions
• On the "generalized Generalized Langevin Equation"
• Nonlinear Response in the Driven Lattice Lorentz Gas
• Colloids dragged through a polymer solution: experiment, theory and simulation
• Probing linear and nonlinear microrheology of viscoelastic fluids
• The modified Langevin description for probes in a nonlinear medium
• Properties of a nonlinear bath: Experiments, theory, and a stochastic Prandtl-Tomlinson model
• Driven probe under harmonic confinement in a colloidal bath
• The Prandtl-Tomlinson model of friction with stochastic driving

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• Recoil of a driven tracer in a correlated medium
• Fluctuations of driven probes reveal nonequilibrium transitions in complex fluids