Diffusion and flow in complex liquids

Makuch, Karol; Hołyst, Robert; Kalwarczyk, Tomasz; Garstecki, Piotr; Brady, John F.

doi:10.1039/c9sm01119f

Cited by 27 publications

(22 citation statements)

References 48 publications

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“…[63] and the general framework for viscosity of Ref. [64]. The results that we provide could form material for an in-depth comparison of PFT and MCT, possibly along the lines of Ref.…”

Section: Discussionmentioning

confidence: 54%

Shear-induced deconfinement of hard disks

Jahreis

Schmidt

2020

Colloid Polym Sci

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Using Brownian dynamics simulations, we investigate the response to shear of a two-dimensional system of quasi-hard disks that are confined in the velocity gradient direction by a smooth external potential. Shearing the confined system leads to a homogenization of the one-body density profile. In order to rationalize this deconfinement effect, we split the internal onebody force field into adiabatic and superadiabatic contributions. We demonstrate that the superadiabatic force field consists of viscous and of structural contributions. We give an empirical scaling law that yields results for the superadiabatic force profiles both in the flow and in the gradient direction, in excellent agreement with the simulation data.

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“…[63] and the general framework for viscosity of Ref. [64]. The results that we provide could form material for an in-depth comparison of PFT and MCT, possibly along the lines of Ref.…”

Section: Discussionmentioning

confidence: 54%

Shear-induced deconfinement of hard disks

Jahreis

Schmidt

2020

Colloid Polym Sci

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“…This might be reasonable in the limit of weak non-Newtonian effects, but may lead to imprecise conclusions for fluid mediums exhibiting strong non-Newtonian behaviour, as the Stokes-Einstein equation fails in describing diffusion in complex media. Recently, Makuch et al (2020) devised a relationship between translational and rotational diffusion coefficients which depends on the size of solute. Such theoretical formulation can provide a database for a precise description of diffusion in various complex fluids.…”

Section: Discussionmentioning

confidence: 99%

“…We also assume the solute molecules, inside and outside the interaction layer, to follow Fickian diffusion with constant diffusivity. It has been reported that the presence of polymers significantly affects the diffusive mass transport in a stagnant polymeric medium (Maldonado-Camargo & Rinaldi 2016; Makuch et al 2020). To our knowledge, there has been no study conducted on the mass transport in sheared complex flows.…”

Section: Active Particle In a Second-order Fluidmentioning

confidence: 99%

Non-Newtonian effects on the slip and mobility of a self-propelling active particle

Choudhary

Renganathan

2020

J. Fluid Mech.

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“…For small tracer particles with λ < 1, however, the tracer particles are significantly affected by the molecular nature of the polymer molecules and the Stokes-Einstein relation ( 36) breaks down [42][43][44]. Physically, the tracer particles experience a reduced effective viscosity η e within the pore space that is smaller than the macroscopic viscosity η [15,45,46]. Figure 4 shows D 22 calculated from (36) with equation ( 15) for the PEG viscosity (dotted curves), along with experimental data for three polymer molecular weights (PEG 200, λ = 0.44; PEG 400, λ = 0.30; and PEG 2000, λ = 0.13).…”

Section: Breakdown Of the Stokes-einstein Equationmentioning

confidence: 99%

Effective hard-sphere model of diffusion in aqueous polymer solutions

Peppin¹

2021

Preprint

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An effective hard-sphere model of the diffusion and cross-diffusion of salt in unentangled polymer solutions is developed. Given the viscosity, sedimentation coefficient and osmotic pressure of the polymer, the model predicts the diffusion and cross-diffusion coefficients as functions of the polymer concentration and molecular weight. The results are compared with experimental data on NaCl diffusion in aqueous polyethylene glycol solutions, showing good agreement at polymer molecular weights up to 400 g/L. At higher molecular weights the model becomes less accurate, likely because of the effects of entanglement. The tracer Fickian diffusivity can be written in the form of a Stokes-Einstein equation containing the solution viscosity. For NaCl diffusion in polyethylene glycol solutions, the Stokes-Einstein equation breaks down as the polymer size increases. Using Batchelor’s viscous correction factor to determine an effective viscosity experienced by the salt ions within the polymer matrix leads to much closer agreement with experiment.

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Diffusion and flow in complex liquids

Abstract: Diffusion of a probe in complex liquids and length scale dependent viscosity.

Cited by 27 publications

References 48 publications

Shear-induced deconfinement of hard disks

Shear-induced deconfinement of hard disks

Non-Newtonian effects on the slip and mobility of a self-propelling active particle

Effective hard-sphere model of diffusion in aqueous polymer solutions

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