Polymer rheology simulations at the meso- and macroscopic scale

Sultan, Eric; Meent, Jan Willem van de; Somfai, Ellák; Morozov, Alexander; Saarloos, Wim van

doi:10.1209/0295-5075/90/64002

Cited by 9 publications

(6 citation statements)

References 31 publications

(69 reference statements)

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“…When increasing the surfactant volume fraction to

, there was near agreement between the theoretical estimate of

in laminar flow and the simulation results over the entire investigated range of

; a transition to turbulence was not observed. This

dependence of the frictional coefficient was also confirmed in previous molecular-simulation [ 62 ] and experimental [ 63 , 64 , 65 ] studies. A saturation concentration of additives (“Virk’s asymptote” [ 66 ]) may appear; however, only two volume fractions of the surfactant were considered in this study.…”

Section: Resultssupporting

confidence: 86%

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Kobayashi

Gomyo

Arai

2021

IJMS

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The phenomenon of drag reduction (known as the “Toms effect”) has many industrial and engineering applications, but a definitive molecular-level theory has not yet been constructed. This is due both to the multiscale nature of complex fluids and to the difficulty of directly observing self-assembled structures in nonequilibrium states. On the basis of a large-scale coarse-grained molecular simulation that we conducted, we propose a possible mechanism of turbulence suppression in surfactant aqueous solution. We demonstrate that maintaining sufficiently large micellar structures and a homogeneous radial distribution of surfactant molecules is necessary to obtain the drag-reduction effect. This is the first molecular-simulation evidence that a micellar structure is responsible for drag reduction in pipe flow, and should help in understanding the mechanisms underlying drag reduction by surfactant molecules under nonequilibrium conditions.

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“…When increasing the surfactant volume fraction to

, there was near agreement between the theoretical estimate of

in laminar flow and the simulation results over the entire investigated range of

; a transition to turbulence was not observed. This

Section: Resultssupporting

confidence: 86%

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Kobayashi

Gomyo

Arai

2021

IJMS

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“…However, for W i>1, f increases indicating more frequent and periodic tumbling. Power law fitting of f vs. W i provides an exponent of 0.68 which is also observed in Brownian dynamics simulations of polymers in dilute solutions [28][29][30][31]. The rotational diffusivity D was obtained from equilibrium simulations as one half of the slope of the linear fit of the mean squared angular displacement vs. time.…”

mentioning

confidence: 68%

Dynamics and Scission of Rodlike Cationic Surfactant Micelles in Shear Flow

2015

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Flow-induced configuration dynamics and scission of rodlike micelles are studied for the first time using molecular dynamics simulations in presence of explicit solvent and salt. Predicted dependence of tumbling frequency and orientation distribution on shear rate S agrees with mesoscopic theories. However, micelle stretching increases the distance between the cationic head groups and adsorbed counter ions, which reduces electrostatic screening and increases the overall energy Φ linearly with micelle length. Micelle scission occurs when Φ exceeds a threshold value, independent of S.

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“…A possible reason for the weak shear thinning in DPD might be that the contribution of the FENE interactions to the zeroshear viscosity is relatively small, comparable in magnitude to the viscosity of the monomer fluid (as can be inferred from the study of mixtures of normal DPD particles and dumbbells in Ref. 15). Note that we present the relative change of the shear viscosity rather than the total viscosity.…”

Section: Discussionmentioning

confidence: 93%

“…This DPD model was recently extended to mixtures of FENE dumbbells and standard DPD particles. 15 The article is organized as follows. In Sec.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale hydrodynamic modeling of a colloid in shear-thinning viscoelastic fluids under shear flow

Run

Winkler

et al. 2011

The Journal of Chemical Physics

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In order to study the dynamics of colloidal suspensions with viscoelastic solvents, a simple mesoscopic model of the solvent is required. We propose to extend the multiparticle collision dynamics (MPC) technique-a particle-based simulation method, which has been successfully applied to study the hydrodynamic behavior of many complex fluids with Newtonian solvent-to shear-thinning viscoelastic solvents. Here, the normal MPC particles are replaced by dumbbells with finite-extensible nonlinear elastic (FENE) springs. We have studied the properties of FENE-dumbbell fluids under simple shear flow with shear rateγ . The stress tensor is calculated, and the viscosity η and the first normal-stress coefficient 1 are obtained. Shear-thinning behavior is found for reduced shear rates =γ τ > 1, where τ is a characteristic dumbbell relaxation time. Here, both η and 1 display power-law behavior in the shear-thinning regime. Thus, the FENE-dumbbell fluid with MPC collisions provides a good description of viscoelastic fluids. As a first application, we study the flow behavior of a colloid in a shear-thinning viscoelastic fluid in two dimensions. A slowing down of the colloid rotation in a viscoelastic fluid compared to a Newtonian fluid is obtained, in agreement with recent numerical calculations and experimental results.

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Polymer rheology simulations at the meso- and macroscopic scale

Cited by 9 publications

References 31 publications

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Dynamics and Scission of Rodlike Cationic Surfactant Micelles in Shear Flow

Mesoscale hydrodynamic modeling of a colloid in shear-thinning viscoelastic fluids under shear flow

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