Intrinsic viscosity of flexible polymers in unbounded and bounded Newtonian shear flow

1991 ◽  
Vol 24 (19) ◽  
pp. 5351-5356 ◽  
Author(s):  
J. H. Van Vliet ◽  
G. Ten Brinke
Keyword(s):  
Shear Flow ◽  
Intrinsic Viscosity ◽  
Flexible Polymers

High-frequency viscosity of a dilute suspension of elongated particles in a linear shear flow between two walls

2014 ◽  
Vol 764 ◽  
pp. 133-147 ◽  
Author(s):  
François Feuillebois ◽  
Maria L. Ekiel-Jeżewska ◽  
Eligiusz Wajnryb ◽  
Antoine Sellier ◽  
Jerzy Bławzdziewicz
Keyword(s):  
Aspect Ratio ◽  
Shear Flow ◽  
Intrinsic Viscosity ◽  
Effective Viscosity ◽  
Geometric Constraints ◽  
Particle Orientation ◽  
Hydrodynamic Coupling ◽  
Linear Shear ◽  
Dilute Suspension ◽  
Particle Length

AbstractA general expression for the effective viscosity of a dilute suspension of arbitrary-shaped particles in linear shear flow between two parallel walls is derived in terms of the induced stresslets on particles. This formula is applied to $N$-bead rods and to prolate spheroids with the same length, aspect ratio and volume. The effective viscosity of non-Brownian particles in a periodic shear flow is considered here. The oscillating frequency is high enough for the particle orientation and centre-of-mass distribution to be practically frozen, yet small enough for the flow to be quasi-steady. It is known that for spheres, the intrinsic viscosity $[{\it\mu}]$ increases monotonically when the distance $H$ between the walls is decreased. The dependence is more complex for both types of elongated particles. Three regimes are theoretically predicted here: (i) a ‘weakly confined’ regime (for $H>l$, where $l$ is the particle length), where $[{\it\mu}]$ is slightly larger for smaller $H$; (ii) a ‘semi-confined’ regime, when $H$ becomes smaller than $l$, where $[{\it\mu}]$ rapidly decreases since the geometric constraints eliminate particle orientations corresponding to the largest stresslets; (iii) a ‘strongly confined’ regime when $H$ becomes smaller than 2–3 particle widths $d$, where $[{\it\mu}]$ rapidly increases owing to the strong hydrodynamic coupling with the walls. In addition, for sufficiently slender particles (with aspect ratio larger than 5–6) there is a domain of narrow gaps for which the intrinsic viscosity is smaller than that in unbounded fluid.

Influence of draining and excluded volume on the intrinsic viscosity of flexible polymers

1985 ◽  
Vol 18 (12) ◽  
pp. 2464-2474 ◽  
Author(s):  
Shi Qing Wang ◽  
Jack F. Douglas ◽  
Karl F. Freed
Keyword(s):  
Intrinsic Viscosity ◽  
Excluded Volume ◽  
Flexible Polymers

Dynamics of individual flexible polymers in a shear flow

Nature ◽  
10.1038/21148 ◽  
1999 ◽  
Vol 399 (6736) ◽  
pp. 564-566 ◽  
Author(s):  
Philip LeDuc ◽  
Charbel Haber ◽  
Gang Bao ◽  
Denis Wirtz
Keyword(s):  
Shear Flow ◽  
Flexible Polymers

The effect of shear flow on the rotational diffusion of a single axisymmetric particle

2015 ◽  
Vol 772 ◽  
pp. 42-79 ◽  
Author(s):  
Brian D. Leahy ◽  
Donald L. Koch ◽  
Itai Cohen
Keyword(s):  
Aspect Ratio ◽  
Shear Flow ◽  
Intrinsic Viscosity ◽  
Strain Amplitude ◽  
Rotational Diffusion ◽  
Oscillatory Shear ◽  
Time Dependent ◽  
Continuous Shear ◽  
Orientation Distributions ◽  
Particle Aspect Ratio

Understanding the orientation dynamics of anisotropic colloidal particles is important for suspension rheology and particle self-assembly. However, even for the simplest case of dilute suspensions in shear flow, the orientation dynamics of non-spherical Brownian particles are poorly understood. Here we analytically calculate the time-dependent orientation distributions for non-spherical axisymmetric particles confined to rotate in the flow–gradient plane, in the limit of small but non-zero Brownian diffusivity. For continuous shear, despite the complicated dynamics arising from the particle rotations, we find a coordinate change that maps the orientation dynamics to a diffusion equation with a remarkably simple ratio of the enhanced rotary diffusivity to the zero shear diffusion: $D_{eff}^{r}/D_{0}^{r}=(3/8)(p-1/p)^{2}+1$, where $p$ is the particle aspect ratio. For oscillatory shear, the enhanced diffusion becomes orientation dependent and drastically alters the long-time orientation distributions. We describe a general method for solving the time-dependent oscillatory shear distributions and finding the effective diffusion constant. As an illustration, we use this method to solve for the diffusion and distributions in the case of triangle-wave oscillatory shear and find that they depend strongly on the strain amplitude and particle aspect ratio. These results provide new insight into the time-dependent rheology of suspensions of anisotropic particles. For continuous shear, we find two distinct diffusive time scales in the rheology that scale separately with aspect ratio $p$, as $1/D_{0}^{r}p^{4}$ and as $1/D_{0}^{r}p^{2}$ for $p\gg 1$. For oscillatory shear flows, the intrinsic viscosity oscillates with the strain amplitude. Finally, we show the relevance of our results to real suspensions in which particles can rotate freely. Collectively, the interplay between shear-induced rotations and diffusion has rich structure and strong effects: for a particle with aspect ratio 10, the oscillatory shear intrinsic viscosity varies by a factor of ${\approx}2$ and the rotational diffusion by a factor of ${\approx}40$.

Understanding conformational and dynamical evolution of semiflexible polymers in shear flow

Soft Matter ◽  
2019 ◽  
Vol 15 (31) ◽  
pp. 6353-6361 ◽  
Author(s):  
Xiangxin Kong ◽  
Yingchun Han ◽  
Wenduo Chen ◽  
Fengchao Cui ◽  
Yunqi Li
Keyword(s):  
Shear Strength ◽  
Shear Flow ◽  
Dynamical Evolution ◽  
Semiflexible Polymers ◽  
Flexible Polymers ◽  
Affine Deformation

At small and intermediate shear strength, flexible polymers show a quasi-affine deformation while semiflexible ones are initially unfolded from the center.

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