scholarly journals Rheology of dense suspensions of elastic capsules: normal stresses, yield stress, jamming and confinement effects

Soft Matter ◽  
2014 ◽  
Vol 10 (24) ◽  
pp. 4360 ◽  
Author(s):  
Markus Gross ◽  
Timm Krüger ◽  
Fathollah Varnik
Keyword(s):  
Yield Stress ◽  
Normal Stresses ◽  
Confinement Effects ◽  
Dense Suspensions ◽  
Elastic Capsules

Rheology in Complex Fluids 1

2019 ◽  
pp. 212-247
Author(s):  
Troy Shinbrot
Keyword(s):  
Liquid Crystal ◽  
Synovial Fluid ◽  
Yield Stress ◽  
Complex Fluids ◽  
Shear Thickening ◽  
Lubrication Approximation ◽  
Complex Flows ◽  
Dense Suspensions ◽  
Crystal Alignment ◽  
Model Equations

Complex flows are described, including shear thinning, shear thickening, and yield-stress. Mechanisms of changing viscosity in dense suspensions are explored, including the relevance of the lubrication approximation, dilatency, and the spaghetti model of polymers. Liquid crystal alignment is discussed, and model equations are introduced for flows in packed beds. The viscosity of synovial fluid is described, and equations to combine viscous and elastic behaviors are obtained.

Effect of normal stresses on yield stress of molybdenum single crystals at slip on the plane (211)

1985 ◽  
Vol 87 (2) ◽  
pp. 559-563 ◽  
Author(s):  
A. V. Dobromyslov ◽  
G. V. Dolgikh ◽  
I. A. Peretubina
Keyword(s):  
Single Crystals ◽  
Yield Stress ◽  
Normal Stresses

scholarly journals Numerical Simulations of the Flow of a Dense Suspension Exhibiting Yield-Stress and Shear-Thinning Effects

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6635
Author(s):  
Meng-Ge Li ◽  
Feng Feng ◽  
Wei-Tao Wu ◽  
Mehrdad Massoudi
Keyword(s):  
Numerical Simulations ◽  
Yield Stress ◽  
Shear Thinning ◽  
Complex Materials ◽  
Flow Disturbance ◽  
Bingham Number ◽  
Dense Suspension ◽  
Dense Suspensions ◽  
High Level ◽  
Nonlinear Fluid

Many types of dense suspensions are complex materials exhibiting both solid-like and fluid-like behavior. These suspensions are usually considered to behave as non-Newtonian fluids and the rheological characteristics such as yield stress, thixotropy and shear-thinning/thickening can have significant impact on the flow and the engineering applications of these materials. Therefore, it is important to understand the rheological features of these fluids. In this paper, we study the flow of a nonlinear fluid which exhibits yield stress and shear-thinning effects. The geometries of interests are a straight channel, a channel with a crevice and a pipe with a contraction; we assume the fluid behaves as a Herschel-Bulkley fluid. The numerical simulations indicate that for flows with low Reynolds number and high Bingham number an unyielded plug may form in the center of the channel. In the case of a channel with a crevice, the fluid in the deep portion of the crevice is at an extremely high level of viscosity, forming a plug which is hard to yield. For the pipe with a contraction, near the pipe neck the unyielded region is smaller due to the enhanced flow disturbance.

An attempt to categorize yield stress fluid behaviour

2009 ◽  
Vol 367 (1909) ◽  
pp. 5139-5155 ◽  
Author(s):  
Peder Moller ◽  
Abdoulaye Fall ◽  
Vijayakumar Chikkadi ◽  
Didi Derks ◽  
Daniel Bonn
Keyword(s):  
Shear Stress ◽  
Experimental Determination ◽  
Yield Stress ◽  
Shear Banding ◽  
Ongoing Debate ◽  
Yield Stress Fluids ◽  
Dense Suspensions ◽  
Experimental Protocols ◽  
Fluid Behaviour

We propose a new view on yield stress materials. Dense suspensions and many other materials have a yield stress—they flow only if a large enough shear stress is exerted on them. There has been an ongoing debate in the literature on whether true yield stress fluids exist, and even whether the concept is useful. This is mainly due to the experimental difficulties in determining the yield stress. We show that most if not all of these difficulties disappear when a clear distinction is made between two types of yield stress fluids: thixotropic and simple ones. For the former, adequate experimental protocols need to be employed that take into account the time evolution of these materials: ageing and shear rejuvenation. This solves the problem of experimental determination of the yield stress. Also, we show that true yield stress materials indeed exist, and in addition, we account for shear banding that is generically observed in yield stress fluids.

Granular Fluids Rheometry

1992 ◽  
Vol 289 ◽  
Author(s):  
G H Meeten ◽  
D Pafitis
Keyword(s):  
Yield Stress ◽  
Power Law ◽  
Coaxial Cylinder ◽  
High Density ◽  
Accurate Data ◽  
Annular Gap ◽  
Dense Suspensions ◽  
Drilling Muds ◽  
Shear History

AbstractMany functional fluids, such as cement slurries or drilling muds, contain high-density solids, typically grains of 10–100 micron in diameter, suspended in a liquid of much lower density. Coaxial cylinder rheometers, conventionally used for oilwell fluids and dense suspensions generally, are shown to give large errors owing to gravitational or centrifugal migration of the high-density solids. Further errors can arise from slippage between the fluid and the smooth walls of the rheometer.A modification is described to a coaxial cylinder rheometer, in which the fluid is circulated, using an external pump, through the sample cup and around the rotor/stator assembly. This circulation mixes and homogenises the fluid, prevents solids build-up in both the annular gap and the cup bottom, and provides an independently-controllable shear history. Thus stable and accurate data can be obtained for fluids which give measurement problems using standard rheometers.Results are given for various power-law/yield stress granular fluids.

Dense suspensions in rotating-rod flows: normal stresses and particle migration

2011 ◽  
Vol 686 ◽  
pp. 5-25 ◽  
Author(s):  
François Boyer ◽  
Olivier Pouliquen ◽  
Élisabeth Guazzelli
Keyword(s):  
Shear Rate ◽  
Normal Stress ◽  
Volume Fraction ◽  
Particle Migration ◽  
Balance Model ◽  
Normal Stresses ◽  
Dense Suspensions ◽  
Normal Stress Differences ◽  
Neutrally Buoyant ◽  
Dependent Behaviour

AbstractNormal stress differences are measured in dense suspensions of neutrally buoyant non-Brownian spheres dispersed in a Newtonian fluid. Rotating-rod rheometry is used to characterize the suspension normal stresses which are responsible for a rod-dipping phenomenon. These normal stress differences are seen to strongly increase above a volume fraction of approximately 22 %. During the course of the experiments, a new time-dependent behaviour is also observed: the dip is filled with increasing times. This time evolution is found to be related to particle migration from regions of high shear rate to regions of low shear rate. The behaviour is compared with the predictions of a suspension balance model in which the particle migration flux is related to the normal stresses of the suspension.

Rheology of dense suspensions of non-colloidal spheres in yield-stress fluids

2015 ◽  
Vol 776 ◽  
Author(s):  
Simon Dagois-Bohy ◽  
Sarah Hormozi ◽  
Élisabeth Guazzelli ◽  
Olivier Pouliquen
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Normal Stress ◽  
Yield Stress ◽  
Rheological Measurements ◽  
Model Based ◽  
Colloidal Spheres ◽  
Yield Stress Fluids ◽  
Dense Suspensions ◽  
Scaling Arguments

Pressure-imposed rheometry is used to study the rheological properties of suspensions of non-colloidal spheres in yield-stress fluids. Accurate measurements for both the shear stress and the particle normal stress are obtained in the dense regime. The rheological measurements are favourably compared with a model based on scaling arguments and homogenisation methods.

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