scholarly journals Correction: Steady shearing flows of deformable, inelastic spheres

Soft Matter ◽  
2015 ◽  
Vol 11 (29) ◽  
pp. 5970-5970 ◽  
Author(s):  
Diego Berzi ◽  
James T. Jenkins
Keyword(s):  
Steady Shearing

Vanadium Pentoxide Gels: Structural Development and Rheological Properties

1990 ◽  
Vol 180 ◽  
Author(s):  
J.K. Bailey ◽  
T. Nagase ◽  
G.A. Pozarnsky ◽  
M.L. Mecartney
Keyword(s):  
Vanadium Pentoxide ◽  
Structural Development ◽  
Small Particles ◽  
Rheological Characterization ◽  
Cryogenic Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Before And After ◽  
Constant Shear Stress ◽  
Steady Shearing ◽  
Rheological Experiments

ABSTRACTCryogenic transmission electron Microscopy (cryo-TEM) and rheological characterization were conducted in order to understand structural development of vanadium pentoxide gels during processing. Sols were prepared by ion exchange from sodium metavanadate solutions. Cryo-TEM revealed that fine threads about 1.5nm wide initially form and grow into ribbons approximately 25nm wide and at least 1000nm long. The threads appear to self assemble into the ribbons. During this structural development, the dynamic viscosity increased. Upon steady shearing of the sols, the system exhibited thixotropy, i.e. the viscosity decreased with time under constant shear stress and subsequently rheopexy, the viscosity increased with time. Comparison of the structure before and after shearing indicated that during the rheological experiments aggregation of small particles or fragments was occurring.

Oscillatory strain with superposed steady shearing in noncolloidal suspensions

2020 ◽  
Vol 64 (5) ◽  
pp. 1087-1106
Author(s):  
Arif Mahmud ◽  
Shaocong Dai ◽  
Roger I. Tanner
Keyword(s):  
Steady Shearing ◽  
Noncolloidal Suspensions

Prediction of the dispersion of particle clusters in the nano-scale—Part I: Steady shearing responses

2006 ◽  
Vol 61 (2) ◽  
pp. 473-488 ◽  
Author(s):  
Maddalena Fanelli ◽  
Donald L. Feke ◽  
Ica Manas-Zloczower
Keyword(s):  
Nano Scale ◽  
Steady Shearing

The Thickness of Steady Plane Shear Flows of Circular Disks Driven by Identical Boundaries

1988 ◽  
Vol 55 (4) ◽  
pp. 969-974 ◽  
Author(s):  
D. M. Hanes ◽  
J. T. Jenkins ◽  
M. W. Richman
Keyword(s):  
Relative Motion ◽  
Constitutive Relations ◽  
Balance Laws ◽  
Plane Shear ◽  
Normal Traction ◽  
Steady Solutions ◽  
Steady Shearing ◽  
Steady Plane ◽  
Steady Motions ◽  
Circular Disks

We employ balance laws and constitutive relations for rapid, dense, plane flows of identical circular disks together with boundary conditions at a bumpy wall to analyse steady shearing flows maintained by the relative motion of two identical, parallel walls. The disks and the walls are assumed to be frictionless and nearly elastic. Given the properties of the flowing disks, those of the boundary, and the ratio of the tangential and normal tractions applied to the boundary, we determine what the distance between the walls must be for a steady solution to be possible. For these steady solutions we relate the velocity of the walls to the normal and tangential tractions applied to them. We find that in certain circumstances steady motions may be maintained even when the ratio of tangential to normal traction is much less than its value in a homogeneous simple shear. In the Appendix, the corresponding results for spheres are outlined.

Non-Newtonian effects in steady motion of some idealized elastico-viscous liquids

1958 ◽  
Vol 245 (1241) ◽  
pp. 278-297 ◽  
Keyword(s):  
Steady Flow ◽  
Apparent Viscosity ◽  
Steady Motion ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Straight Pipe ◽  
Shearing Flow ◽  
Viscous Liquids ◽  
Variable Shear ◽  
Steady Shearing

Normal-stress effects and the variation of apparent viscosity with rate of shear in simple types of steady flow of certain idealized elastico-viscous liquids are discussed. The liquids are those whose behaviour at sufficiently small variable shear stresses can be characterized by three constants (a coefficient of viscosity, a relaxation time and a retardation time) and whose invariant differential equations of state for general motion (involving eight independent physical constants) are linear in the stresses and include terms of no higher degree than the second in the stresses and velocity gradients together. The normal stresses which, in addition to shear stresses, are present in such a liquid in a state of simple shearing flow, or in flow in a circular pipe, or between rotating cylinders, are investigated; and the conditions under which the Weissenberg climbing effect will occur, in a positive or negative sense, are examined. In many liquids of this class, steady rectilinear flow under a uniform pressure gradient is not always possible in a straight pipe of arbitrary section, nor is steady flow in horizontal circles in a region bounded by arbitrary surfaces of revolution in relative rotation about common vertical axis. The behaviour of these idealized liquids when sheared in a narrow gap between a rotating wide-angled cone and a flat plate is compared with the observations of Roberts (1952, 1953) on some real elastico-viscous liquids. Certain liquids of this class, characterized by six independent constants satisfying certain inequalities, exhibit rheological behaviour which is, at least qualitatively, similar to the behaviour of many real elastico-viscous liquids in the following respects: the behaviour at small variable shear stresses, the variation of apparent viscosity with rate of steady shearing, the climbing effect up a vertical rod rotated in the liquid, and a distribution of normal stresses equivalent to an extra tension along the streamlines (with an isotropic state of stress in the plane normal to the streamlines) which is present in all the simple types of steady shearing flow investigated. These liquids can flow steadily in straight lines through a straight pipe of any section.

scholarly journals Mechanical properties of brain tubulin and microtubules.

1988 ◽  
Vol 106 (4) ◽  
pp. 1205-1211 ◽  
Author(s):  
M Sato ◽  
W H Schwartz ◽  
S C Selden ◽  
T D Pollard
Keyword(s):  
Mechanical Properties ◽  
Viscoelastic Properties ◽  
Microtubule Assembly ◽  
Cross Link ◽  
Microtubule Associated Proteins ◽  
Heat Stable ◽  
Microtubule Protein ◽  
Associated Proteins ◽  
Steady Shearing ◽  
Brain Tubulin

We measured the elasticity and viscosity of brain tubulin solutions under various conditions with a cone and plate rheometer using both oscillatory and steady shearing modes. Microtubules composed of purified tubulin, purified tubulin with taxol and 3x cycled microtubule protein from pig, cow, and chicken behaved as mechanically indistinguishable viscoelastic materials. Microtubules composed of pure tubulin and heat stable microtubule-associated proteins were also similar but did not recover their mechanical properties after shearing like other samples, even after 60 min. All of the other microtubule samples were more rigid after flow orientation, suggesting that the mechanical properties of anisotropic arrays of microtubules may be substantially greater than those of randomly arranged microtubules. These experiments confirm that MAPs do not cross link microtubules. Surprisingly, under conditions where microtubule assembly is strongly inhibited (either 5 degrees or at 37 degrees C with colchicine or Ca++) tubulin was mechanically indistinguishable from microtubules at 10-20 microM concentration. By electron microscopy and ultracentrifugation these samples were devoid of microtubules or other obvious structures. However, these mechanical data are strong evidence that tubulin will spontaneously assemble into alternate structures (aggregates) in nonpolymerizing conditions. Because unpolymerized tubulin is found in significant quantities in the cytoplasm, it may contribute significantly to the viscoelastic properties of cytoplasm, especially at low deformation rates.

Yield Stress of Emulsions and Suspensions as Measured in Steady Shearing and in Oscillations

2008 ◽  
Vol 18 (4) ◽  
pp. 44790-1-44790-8 ◽  
Author(s):  
I. Masalova ◽  
A.Ya. Malkin ◽  
R. Foudazi
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Flow Curves ◽  
Dynamic Yield Stress ◽  
Shear Rates ◽  
Meaningful Material ◽  
Dynamic Yield ◽  
Steady Shearing ◽  
Concentrated Emulsions

Abstract The yield stresses of five samples (two highly concentrated emulsions, two Kaolin dispersions and mayonnaise) were determined in two ways. In one case, steady shear experiments were performed over a range of incrementally decreasing shear rates. The resulting flow curves, plotted as shear stress against shear rate, clearly showed the existence of a yield stress for each sample, the Herschel-Bulkley model being fitted to obtain values. In the second case, oscillatory amplitude sweeps were performed at three frequencies, and the “dynamic yield stress” was defined as the stress at which deviation from linearity occurred; this procedure has often been used to determine the yield stress of emulsions. It was found that the dynamic yield stress is frequency dependent, and cannot therefore be thought of as physically meaningful material property. At no frequency did the dynamic yield stress correlate with the yield stress obtained from the flow curves.

scholarly journals A general fluid–sediment mixture model and constitutive theory validated in many flow regimes

2018 ◽  
Vol 861 ◽  
pp. 721-764 ◽  
Author(s):  
Aaron S. Baumgarten ◽  
Ken Kamrin
Keyword(s):  
Constitutive Model ◽  
Equations Of Motion ◽  
Material Point ◽  
Mixed System ◽  
Two Phase ◽  
Mixture Phase ◽  
State Behaviour ◽  
Steady Shearing ◽  
Basic Equations ◽  
Sediment Mixture

We present a thermodynamically consistent constitutive model for fluid-saturated sediments, spanning dense to dilute regimes, developed from the basic balance laws for two-phase mixtures. The model can represent various limiting cases, such as pure fluid and dry grains. It is formulated to capture a number of key behaviours such as: (i) viscous inertial rheology of submerged wet grains under steady shearing flows, (ii) the critical state behaviour of grains, which causes granular Reynolds dilation/contraction due to shear, (iii) the change in the effective viscosity of the fluid due to the presence of suspended grains and (iv) the Darcy-like drag interaction observed in both dense and dilute mixtures, which gives rise to complex fluid–grain interactions under dilation and flow. The full constitutive model is combined with the basic equations of motion for each mixture phase and implemented in the material point method (MPM) to accurately model the coupled dynamics of the mixed system. Qualitative results show the breadth of problems which this model can address. Quantitative results demonstrate the accuracy of this model as compared with analytical limits and experimental observations of fluid and grain behaviours in inhomogeneous geometries.

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