Steady shearing flow of a moderately entangled polyethylene liquid

2016 ◽  
Vol 60 (6) ◽  
pp. 1227-1244 ◽  
Author(s):  
M. H. Nafar Sefiddashti ◽  
B. J. Edwards ◽  
B. Khomami
Keyword(s):  
Shearing Flow ◽  
Steady Shearing

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.

Flow Behavior of Polystyrene Systems in Steady Shearing Flow

1969 ◽  
Vol 2 (1) ◽  
pp. 49-57 ◽  
Author(s):  
William W. Graessley ◽  
Leon Segal
Keyword(s):  
Flow Behavior ◽  
Shearing Flow ◽  
Steady Shearing

Experimental Analysis of the Slip Phenomenon of Sewage Sludge

2011 ◽  
Vol 243-249 ◽  
pp. 41-44
Author(s):  
Li Zhang ◽  
Min Quan Feng ◽  
Xiao Bin Zhang
Keyword(s):  
Water Content ◽  
Strain Amplitude ◽  
High Speed ◽  
Stress Amplitude ◽  
Wall Slip ◽  
Shearing Flow ◽  
Oscillatory Shear Flow ◽  
Straight Line ◽  
Strain Stress ◽  
Steady Shearing

Wall slip of sweage sludge and affect slip possible factors were studied experimentally by using a rotational rheometer with parallel plate fixtures and by means high speed camera. In the steady shearing flow, the technique involves placing a straight line marker monitoring of wall slip,checking the gap dependence of the stress/ strain data. For sweage sludge of water content 80%, in the shearing flow it was found that, as the strain amplitude increasing, the stress data obtained at different gaps, then, at the certain strain amplitude, started to diverge, indicating that wall slip occurred. But for sweage sludge of water content 90%, these curves are superimpose, indicating no slip occurred. In the dynamic oscillatory shear flow, we analyze the total wave. While strain, stress amplitude decreases with the time, while strain, the stress amplitude remains constant.

Stochastic Aspects of Bridging Bonds of Induced Structure of Electro-Rheological Fluids in Shear Flow

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1798-1805 ◽  
Author(s):  
P. Riha ◽  
H. Kimura ◽  
J. Takimoto ◽  
K. Koyama
Keyword(s):  
Flow Behavior ◽  
Electrorheological Fluid ◽  
Rheological Characteristics ◽  
Rheological Equation ◽  
Shearing Flow ◽  
Polymeric Blends ◽  
Start Up ◽  
Dominant Feature ◽  
Steady Shearing ◽  
Induced Structure

The bridging of electrodes by clusters of polarizable elements occurs to be a dominant feature of the response of certain electrorheological fluid suspensions and liquid polymeric blends to the imposed electric field. The evolution of the bridging structure in deformation and flow is described as a stochastic process and identified with the macroscopic flow behavior. The effect of structure is introduced into the rheological equation providing its non-linear modification. The comparisons are presented showing how the proposed rheological equation describes rheological characteristics measured at steady shearing flow and start-up shearing flow.

Theory of dilute electro-rheological fluids

1991 ◽  
Vol 434 (1891) ◽  
pp. 297-315 ◽  
Keyword(s):  
Electric Field ◽  
Transverse Electric ◽  
Spherical Particles ◽  
Dielectric Fluid ◽  
General Study ◽  
Shearing Flow ◽  
Strain Relationship ◽  
Dilute Suspension ◽  
Steady Shearing ◽  
The Relationship

The stress versus rate of strain relationship for a dilute suspension of conducting spherical particles in a dielectric fluid is worked out under conditions of simple steady shearing flow in a transverse electric field. The relationship is found to be nonlinear and multivalued so that under certain simple circumstances hysteresis and catastrophic changes in stress or strain rate can occur. The work is of interest in the general study of electro-rheological fluids.

Self-diffusion of bimodal suspensions of hydrodynamically interacting spherical particles in shearing flow

1994 ◽  
Vol 281 ◽  
pp. 51-80 ◽  
Author(s):  
Chingyi Chang ◽  
Robert L. Powell
Keyword(s):  
Diffusion Coefficients ◽  
Cluster Size ◽  
Near Field ◽  
Spherical Particles ◽  
Random Structure ◽  
Shearing Flow ◽  
Self Diffusion ◽  
Long Time ◽  
Mobility Matrix ◽  
Many Body Interactions

We study the average mobilities and long-time self-diffusion coefficients of a suspension of bimodally distributed spherical particles. Stokesian dynamics is used to calculate the particle trajectories for a monolayer of bimodal-sized spheres. Hydrodynamic forces only are considered and they are calculated using the inverse of the grand mobility matrix for far-field many-body interactions and lubrication formulae for near-field effects. We determine both the detailed microstructure (e.g. the pair-connectedness function and cluster formation) and the macroscopic properties (e.g. viscosity and self-diffusion coefficients). The flow of an ‘infinite’ suspension is simulated by considering 25, 49, 64 and 100 particles to be one ‘cell’ of a periodic array. Effects of both the size ratio and the relative fractions of the different-sized particles are examined. For the microstructures, the pair-connectedness function shows that the particles form clusters in simple shearing flow due to lubrication forces. The nearly symmetric angular structures imply the absence of normal stress differences for a suspension with purely hydrodynamic interactions between spheres. For average mobilities at infinite Péclet number, Ds0, our simulation results suggest that the reduction of Ds0 as concentration increases is directly linked to the influence of particle size distribution on the average cluster size. For long-time self-diffusion coefficients, Ds∞, we found good agreement between simulation and experiment (Leighton & Acrovos 1987 a; Phan and Leighton 1993) for monodispersed suspensions. For bimodal suspensions, the magnitude of Ds∞, and the time to reach the asymptotic diffusive behaviour depend on the cluster size formed in the system, or the viscosity of the suspension. We also consider the effect of the initial configuration by letting the spheres be both organized (size segregated) and randomly placed. We find that it takes a longer time for a suspension with an initially organized structure to achieve steady state than one with a random structure.

Effect of Shear Surface Boundaries on Stress for Shearing Flow of Dry Metal Powders—An Experimental Study

1987 ◽  
Vol 109 (2) ◽  
pp. 232-237 ◽  
Author(s):  
K. Craig ◽  
R. H. Buckholz ◽  
G. Domoto
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Normal Stress ◽  
Particle Diameter ◽  
Surface Boundary ◽  
Metal Powders ◽  
Shear Surface ◽  
Shear Cell ◽  
Shearing Flow ◽  
Solids Content

This paper studies the rapid simple shearing flow of dry cohesionless metal powders contained between parallel rotating plates. In this study, an annular shear cell test apparatus was used; the dry metal powders are rapidly sheared by rotating one of the shear surfaces while the other shear surface remains fixed. Such a flow geometry is of interest to tribologists working in the area of dry or powder lubrication. The shear stress and normal stress on the stationary surface are measured as a function of the following parameters: shear surface boundary material and roughness, the shear-cell gap thickness, the shear-rate and the fractional solids content. Both the fractional solids content and the gap thickness are kept at prescribed values during stress measurements. In this experiment the metal powder tested is different from the shear transmission surface material; the effect on the measured normal and shear stress data are reported. The results show the dependence of the normal stress and the shear stress on the shear-rate, particle density and particle diameter. Likewise, a significant stress dependence on both the fractional solids content and the shear-cell gap thickness was observed.

scholarly journals Response of monoflagellate pullers to a shearing flow: A simulation study of microswimmer guidance

2018 ◽  
Vol 98 (6) ◽  
Author(s):  
Benjamin J. Walker ◽  
Kenta Ishimoto ◽  
Richard J. Wheeler ◽  
Eamonn A. Gaffney
Keyword(s):  
Simulation Study ◽  
Shearing Flow

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.

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