scholarly journals Viscoelastic flow past mono- and bidisperse random arrays of cylinders: flow resistance, topology and normal stress distribution

Soft Matter ◽  
2017 ◽  
Vol 13 (48) ◽  
pp. 9138-9146 ◽  
Author(s):  
S. De ◽  
J. A. M. Kuipers ◽  
E. A. J. F. Peters ◽  
J. T. Padding
Keyword(s):  
Flow Resistance ◽  
Master Curve ◽  
Characteristic Length ◽  
Deborah Number ◽  
Viscoelastic Flow ◽  
Viscoelastic Flows ◽  
Normal Stress Distribution ◽  
Random Arrays ◽  
Single Master Curve ◽  
Resistance Curves

Different flow resistance curves for viscoelastic flows through random arrangements of cylinders collapse to a single master curve when plotted against a Deborah number based on the square root of the permeability as characteristic length scale.

scholarly journals Astral hydrogels mimic tissue mechanics by aster-aster interpenetration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qingqiao Xie ◽  
Yuandi Zhuang ◽  
Gaojun Ye ◽  
Tiankuo Wang ◽  
Yi Cao ◽  
...  
Keyword(s):  
Common Core ◽  
Self Assembly ◽  
Master Curve ◽  
Soft Tissues ◽  
Tissue Mechanics ◽  
Fresh Perspective ◽  
Single Master Curve ◽  
Unique Mechanism ◽  
Gel Network

AbstractMany soft tissues are compression-stiffening and extension-softening in response to axial strains, but common hydrogels are either inert (for ideal chains) or tissue-opposite (for semiflexible polymers). Herein, we report a class of astral hydrogels that are structurally distinct from tissues but mechanically tissue-like. Specifically, hierarchical self-assembly of amphiphilic gemini molecules produces radial asters with a common core and divergently growing, semiflexible ribbons; adjacent asters moderately interpenetrate each other via interlacement of their peripheral ribbons to form a gel network. Resembling tissues, the astral gels stiffen in compression and soften in extension with all the experimental data across different gel compositions collapsing onto a single master curve. We put forward a minimal model to reproduce the master curve quantitatively, underlying the determinant role of aster-aster interpenetration. Compression significantly expands the interpenetration region, during which the number of effective crosslinks is increased and the network strengthened, while extension does the opposite. Looking forward, we expect this unique mechanism of interpenetration to provide a fresh perspective for designing and constructing mechanically tissue-like materials.

Universality of fractal aggregates as probed by light scattering

1989 ◽  
Vol 423 (1864) ◽  
pp. 71-87 ◽  
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Master Curve ◽  
Rotational Diffusion ◽  
Fractal Dimensions ◽  
Scattering Data ◽  
Diffusion Limited ◽  
Single Master Curve ◽  
Using Data ◽  
Dynamic Light Scattering Data

Fractal colloid aggregates are studied with both static and dynamic light scattering. The dynamic light scattering data are scaled onto a single master curve, whose shape is sensitive to the structure of the aggregates and their mass distribution. By using the structure factor determined from computer-simulated aggregates, and including the effects of rotational diffusion, we predict the shape of the master curve for different cluster distributions. Excellent agreement is found between our predictions and the data for the two limiting régimes, diffusion-limited and reaction-limited colloid aggregation. Furthermore, using data from several completely different colloids, we find that the shapes of the master curves are identical for each régime. In addition, the cluster fractal dimensions and the aggregation kinetics are identical in each régime. This provides convincing experimental evidence of the universality of these two régimes of colloid aggregation.

The Mechanism of Size-Based Particle Separation by Dielectrophoresis in the Viscoelastic Flows

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Teng Zhou ◽  
Yongbo Deng ◽  
Hongwei Zhao ◽  
Xianman Zhang ◽  
Liuyong Shi ◽  
...  
Keyword(s):  
Electric Field ◽  
Newtonian Fluid ◽  
Finite Size ◽  
Particle Separation ◽  
Weissenberg Number ◽  
Viscoelastic Flow ◽  
Viscoelastic Flows ◽  
Arbitrary Lagrangian Eulerian ◽  
Particle Movement ◽  
Physical Insight

Viscoelastic solution is encountered extensively in microfluidics. In this work, the particle movement of the viscoelastic flow in the contraction–expansion channel is demonstrated. The fluid is described by the Oldroyd-B model, and the particle is driven by dielectrophoretic (DEP) forces induced by the applied electric field. A time-dependent multiphysics numerical model with the thin electric double layer (EDL) assumption was developed, in which the Oldroyd-B viscoelastic fluid flow field, the electric field, and the movement of finite-size particles are solved simultaneously by an arbitrary Lagrangian–Eulerian (ALE) numerical method. By the numerically validated ALE method, the trajectories of particle with different sizes were obtained for the fluid with the Weissenberg number (Wi) of 1 and 0, which can be regarded as the Newtonian fluid. The trajectory in the Oldroyd-B flow with Wi = 1 is compared with that in the Newtonian fluid. Also, trajectories for different particles with different particle sizes moving in the flow with Wi = 1 are compared, which proves that the contraction–expansion channel can also be used for particle separation in the viscoelastic flow. The above results for this work provide the physical insight into the particle movement in the flow of viscous and elastic features.

Lack of null controllability of viscoelastic flows

2019 ◽  
Vol 25 ◽  
pp. 60
Author(s):  
Debayan Maity ◽  
Debanjana Mitra ◽  
Michael Renardy
Keyword(s):  
Approximate Controllability ◽  
Momentum Equation ◽  
Null Controllability ◽  
Viscoelastic Flow ◽  
Viscoelastic Flows ◽  
Relaxation Mode ◽  
Maxwell Fluids ◽  
Linear Viscoelastic ◽  
Exact Null Controllability

We consider controllability of linear viscoelastic flow with a localized control in the momentum equation. We show that, for Jeffreys fluids or for Maxwell fluids with more than one relaxation mode, exact null controllability does not hold. This contrasts with known results on approximate controllability.

Rupture Process During Drop Coalescence

2005 ◽  
Author(s):  
H. Aryafar ◽  
H. P. Kavehpour
Keyword(s):  
Physical Properties ◽  
High Speed ◽  
Master Curve ◽  
Digital Camera ◽  
Planar Interface ◽  
Dimensionless Time ◽  
Film Rupture ◽  
Hole Radius ◽  
Dependent Behavior ◽  
Single Master Curve

During the coalescence of a drop with a planar interface, a hole is generated in a microscopic film that separates the drop from the interface. An experimental study has been performed to investigate the time dependent behavior of the radius of the hole generated during coalescence. The study consisted of placing drops of various sizes and physical properties on a planar interface. The coalescence process was recorded from underneath the interface with the aid of a high speed digital camera and a prism. The experiment captured two separate processes, film rupture and the closing of the hole. During the film rupture, the hole radius demonstrated a power law time dependence. Dimensional analysis showed the percentage of time the hole used to reach its maximum radius was approximately constant for all drops. Moreover, all dimensionless drop rupture radii and times fit onto a single master curve and were independent of their physical properties during the opening. However during the closing of the hole, the dimensionless time and radii did not fit a master curve analogous to the hole rupture. The closing of the hole is an entirely different event from the opening and is governed by different parameters.

Cold Rolling of Foil

1992 ◽  
Vol 206 (2) ◽  
pp. 119-131 ◽  
Author(s):  
N A Fleck ◽  
K L Johnson ◽  
M E Mear ◽  
L C Zhang
Keyword(s):  
Cold Rolling ◽  
Constant Coefficient ◽  
Coulomb Friction ◽  
Master Curve ◽  
Critical Value ◽  
Neutral Zone ◽  
Entry And Exit ◽  
Wide Range ◽  
Dimensional Parameters ◽  
Single Master Curve

A theory of cold rolling of thin gauge strip is presented which, within the idealizations of homogeneous deformation and a constant coefficient of Coulomb friction, rigorously models the elastic deformation of the rolls and the frictional traction at the interface. In contrast with classical theories (3) it is shown that, for gauges less than a critical value, plastic reduction takes place in two zones, at entry and exit, which are separated by a neutral zone in which the rolls are compressed fiat and there is no slip between the rolls and the strip. Roll load and torque are governed by five independent non-dimensional parameters which express the influence of gauge, reduction, friction and front and back tensions. Values of load and torque have been computed (for zero front and back tensions) for a wide range of thickness, reduction and friction and have been found to collapse approximately on to a single master curve.

A numerical study of viscoelastic effects in chaotic mixing between eccentric cylinders

2000 ◽  
Vol 412 ◽  
pp. 197-225 ◽  
Author(s):  
YURUN FAN ◽  
ROGER I. TANNER ◽  
NHAN PHAN-THIEN
Keyword(s):  
Shear Thinning ◽  
Periodic Points ◽  
Deborah Number ◽  
Viscoelastic Flow ◽  
Chaotic Mixing ◽  
Periodic Flow ◽  
Passive Tracer ◽  
Newtonian Flow ◽  
Transient Period ◽  
The Mean

In this paper, we are concerned with the effect of fluid elasticity and shear-thinning viscosity on the chaotic mixing of the flow between two eccentric, alternately rotating cylinders. We employ the well-developed h-p finite element method to achieve a high accuracy and efficiency in calculating steady solutions, and a full unsteady algorithm for creeping viscoelastic flows to study the transient process in this periodic viscoelastic flow. Since the distribution of periodic points of the viscoelastic flow is not symmetric, we have developed a domain-search algorithm based on Newton iteration for locating the periodic points. With the piecewise-steady approximation, our computation for the upper-convected Maxwell fluid predicts no noticeable changes of the advected coverage of a passive tracer from Newtonian flow, with elasticity levels up to a Deborah number of 1.0. The stretching of the fluid elements, quantified by the geometrical mean of the spatial distribution, remains exponential up to a Deborah number of 6.0, with only slight changes from Newtonian flow. On the other hand, the shear-thinning viscosity, modelled by the Carreau equation, has a large impact on both the advection of a passive tracer and the mean stretching of the fluid elements. The creeping, unsteady computations show that the transient period of the velocity is much shorter than the transient period of the stress, and from a pragmatic point of view, this transient process caused by stress relaxation due to sudden switches of the cylinder rotation can be neglected for predicting the advective mixing in this time- periodic flow. The periodic points found up to second order and their eigenvalues are indeed very informative in understanding the chaotic mixing patterns and the qualitative changes of the mean stretching of the fluid elements. The comparison between our computations and those of Niederkorn & Ottino (1993) reveals the importance of reducing the discretization error in the computation of chaotic mixing. The causes of the discrepancy between our prediction of the tracer advection and Niederkorn & Ottino's (1993) experiment are discussed, in which the influence of the shear-thinning first normal stress difference is carefully examined. The discussion leads to questions on whether small elasticity of the fluid has a large effect on the chaotic mixing in this periodic flow.

Simulations of three-dimensional viscoelastic flows past a circular cylinder at moderate Reynolds numbers

2010 ◽  
Vol 651 ◽  
pp. 415-442 ◽  
Author(s):  
DAVID RICHTER ◽  
GIANLUCA IACCARINO ◽  
ERIC S. G. SHAQFEH
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Viscoelastic Flow ◽  
Dimensional Structure ◽  
Recirculation Region ◽  
Viscoelastic Flows ◽  
Cylinder Wake ◽  
Complex Flows

The results from a numerical investigation of inertial viscoelastic flow past a circular cylinder are presented which illustrate the significant effect that dilute concentrations of polymer additives have on complex flows. In particular, effects of polymer extensibility are studied as well as the role of viscoelasticity during three-dimensional cylinder wake transition. Simulations at two distinct Reynolds numbers (Re = 100 and Re = 300) revealed dramatic differences based on the choice of the polymer extensibility (L2 in the FENE-P model), as well as a stabilizing tendency of viscoelasticity. For the Re = 100 case, attention was focused on the effects of increasing polymer extensibility, which included a lengthening of the recirculation region immediately behind the cylinder and a sharp increase in average drag when compared to both the low extensibility and Newtonian cases. For Re = 300, a suppression of the three-dimensional Newtonian mode B instability was observed. This effect is more pronounced for higher polymer extensibilities where all three-dimensional structure is eliminated, and mechanisms for this stabilization are described in the context of roll-up instability inhibition in a viscoelastic shear layer.

scholarly journals Tuning transcriptional regulation through signaling: A predictive theory of allosteric induction

2017 ◽  
Author(s):  
Manuel Razo-Mejia ◽  
Stephanie L. Barnes ◽  
Nathan M. Belliveau ◽  
Griffin Chure ◽  
Tal Einav ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Master Curve ◽  
Dynamic Range ◽  
Large Range ◽  
Input Output ◽  
Copy Numbers ◽  
Analytic Expressions ◽  
Domains Of Life ◽  
Single Master Curve ◽  
Predictive Theory

AbstractAllosteric regulation is found across all domains of life, yet we still lack simple, predictive theories that directly link the experimentally tunable parameters of a system to its input-output response. To that end, we present a general theory of allosteric transcriptional regulation using the Monod-Wyman-Changeux model. We rigorously test this model using the ubiquitous simple repression motif in bacteria by first predicting the behavior of strains that span a large range of repressor copy numbers and DNA binding strengths and then constructing and measuring their response. Our model not only accurately captures the induction profiles of these strains but also enables us to derive analytic expressions for key properties such as the dynamic range and [EC50]. Finally, we derive an expression for the free energy of allosteric repressors which enables us to collapse our experimental data onto a single master curve that captures the diverse phenomenology of the induction profiles.

Sign in / Sign up

Export Citation Format

Share Document