scholarly journals Density waves in shear-thickening suspensions

2020 ◽  
Vol 6 (16) ◽  
pp. eaay5589 ◽  
Author(s):  
Guillaume Ovarlez ◽  
Anh Vu Nguyen Le ◽  
Wilbert J. Smit ◽  
Abdoulaye Fall ◽  
Romain Mari ◽  
...  
Keyword(s):  
Complex Dynamics ◽  
Fresh Concrete ◽  
Shear Thickening ◽  
Density Fluctuations ◽  
Periodic Waves ◽  
Normal Stresses ◽  
Concentrated Suspensions ◽  
Small Areas ◽  
Azimuthal Symmetry ◽  
Silica Suspensions

Shear thickening corresponds to an increase of the viscosity as a function of the shear rate. It is observed in many concentrated suspensions in nature and industry: water or oil saturated sediments, crystal-bearing magma, fresh concrete, silica suspensions, and cornstarch mixtures. Here, we reveal how shear-thickening suspensions flow, shedding light onto as yet non-understood complex dynamics reported in the literature. When shear thickening is important, we show the existence of density fluctuations that appear as periodic waves moving in the direction of flow and breaking azimuthal symmetry. They come with strong normal stress fluctuations of the same periodicity. The flow includes small areas of normal stresses of the order of tens of kilopascals and areas of normal stresses of the order of hundreds of pascals. These stress inhomogeneities could play an important role in the damage caused by thickening fluids in the industry.

Microstructure of shear-thickening concentrated suspensions determined by flow-USANS

2009 ◽  
Vol 48 (8) ◽  
pp. 897-908 ◽  
Author(s):  
Dennis P. Kalman ◽  
Norman J. Wagner
Keyword(s):  
Shear Thickening ◽  
Concentrated Suspensions

Dynamics and structure of an apolar active suspension in an annulus

2017 ◽  
Vol 835 ◽  
pp. 393-405 ◽  
Author(s):  
Sheng Chen ◽  
Peng Gao ◽  
Tong Gao
Keyword(s):  
Complex Dynamics ◽  
Travelling Waves ◽  
Travelling Wave ◽  
Coarse Grained ◽  
Structure Evolution ◽  
Concentrated Suspensions ◽  
Chaotic Flows ◽  
Active Particles ◽  
Crystal Model ◽  
Dilute Suspensions

We study the complex dynamics of a two-dimensional suspension comprising non-motile active particles confined in an annulus. A coarse-grained liquid crystal model is employed to describe the nematic structure evolution, and is hydrodynamically coupled with the Stokes equation to solve for the induced active flows in the annulus. For dilute suspensions, coherent structures are captured by varying the particle activity and gap width, including unidirectional circulations, travelling waves and chaotic flows. For concentrated suspensions, the internal collective dynamics features motile disclination defects and flows at finite gap widths. In particular, we observe an intriguing quasi-steady-state at certain gap widths during which $+1/2$-order defects oscillate around equilibrium positions accompanying travelling-wave flows that switch circulating directions periodically. We perform linear stability analyses to reveal the underlying physical mechanisms of pattern formation during a concatenation of instabilities.

Normal stresses in shear thickening granular suspensions

Soft Matter ◽  
2017 ◽  
Vol 13 (20) ◽  
pp. 3734-3740 ◽  
Author(s):  
Zhongcheng Pan ◽  
Henri de Cagny ◽  
Mehdi Habibi ◽  
Daniel Bonn
Keyword(s):  
Shear Thickening ◽  
Normal Stresses ◽  
Granular Suspensions

scholarly journals Load of gondola with floor decking at handling operations

2015 ◽  
Vol 2015 (4) ◽  
pp. 45-49
Author(s):  
Владимир Кобищанов ◽  
Vladimir Kobishchanov ◽  
Кирилл Герасимов ◽  
Kirill Gerasimov ◽  
Дмитрий Расин ◽  
...  
Keyword(s):  
Maximum Stress ◽  
The Body ◽  
Dynamic Loads ◽  
Normal Stresses ◽  
Test Results ◽  
Load Drop ◽  
Small Areas ◽  
Car Body ◽  
Deflected Mode ◽  
Solid Type

A gondola with a body of solid type – an eco-nomically effective unit of a rollingstock. Most of the damages of gondola bodies is caused at handling operations with the failure of requirements observance established. In the paper the assessment of deflected mode body in the body at the lump load drop with the mass of 500 kg is carried out. Normal stresses and travels arising at the blow of load in the sections of joints of frame beams between each other, side and end walls are analyzed. The values of stresses three times higher than the foreseen ones with “Standards…” are adopted as reference valuations. It is substantiated by test results and the comparison of material characteristics at deadweight and dynamic loads. As a result of car body multichoice computations on basis of the detailed MCE there was established the following: the closer the place of a lump blow to a supporting longitudinal to the car body end is, the stresses are higher in it. Stresses arising in the supporting longitudinal situated between an end girder and a body bolster beam reach 998 H/mm, at the same time in the middle of the car body of a gondola they do not exceed 450 H⁄mm². If a load lump falls down on the joint of cross-beams and longitudinal ones, then stresses in their sections 10-15 times less, than if the fall were to a strengthening beam. In the main the maximum stress distribution is limited by small areas located between two neighboring crossbeams. The research results have shown, it is necessary that additional bearing elements absorbing a blow should be introduced in a frame.

Transient Study on the Shear Thickening Behaviour of Surface Modified Fumed Silica Suspensions in Polypropylene Glycol

2008 ◽  
Author(s):  
F. J. Galindo-Rosales ◽  
F. J. Rubio-Hernández ◽  
Albert Co ◽  
Gary L. Leal ◽  
Ralph H. Colby ◽  
...  
Keyword(s):  
Fumed Silica ◽  
Shear Thickening ◽  
Polypropylene Glycol ◽  
Transient Study ◽  
Surface Modified ◽  
Silica Suspensions

Rheological Properties of Dense Silica Suspensions

1992 ◽  
Vol 289 ◽  
Author(s):  
J. Chappuis ◽  
D. Guinot ◽  
P. Leture
Keyword(s):  
Rheological Properties ◽  
Silica Particles ◽  
Point Of Zero Charge ◽  
Concentrated Suspensions ◽  
Zero Charge ◽  
Ph Conditions ◽  
Silica Suspensions

AbstractThe rheological properties and microstructure of concentrated suspensions of silica particles in water have been studied. Two typical pH conditions, the effect of the addition of CaCl2 and different mixing procedures have been investigated. When CaCl2 is added, the suspensions become very thick only if the pH is far from the point of zero charge.

scholarly journals Dipolophoresis in concentrated suspensions of ideally polarizable spheres

2019 ◽  
Vol 875 ◽  
Author(s):  
Siamak Mirfendereski ◽  
Jae Sung Park
Keyword(s):  
Large Scale ◽  
Volume Fraction ◽  
Local Maximum ◽  
Close Packing ◽  
Density Fluctuations ◽  
Distribution Functions ◽  
Spherical Particles ◽  
Concentrated Suspensions ◽  
Induced Charge ◽  
Pair Distribution Functions

The dynamics of ideally polarizable spherical particles in concentrated suspensions under the effects of nonlinear electrokinetic phenomena is analysed using large-scale numerical simulations. Particles are assumed to carry no net charge and considered to undergo the combination of dielectrophoresis and induced-charge electrophoresis termed dipolophoresis. Chaotic motion and resulting hydrodynamic diffusion are known to be driven by the induced-charge electrophoresis, which dominates the dielectrophoresis. Up to a volume fraction $\unicode[STIX]{x1D719}\approx 35\,\%$, the particle dynamics seems to be hindered by the increase in the magnitude of excluded volume interactions with concentration. However, a non-trivial suspension behaviour is observed in concentrated regimes, where the hydrodynamic diffusivity starts to increase with the volume fraction at $\unicode[STIX]{x1D719}\approx 35\,\%$, before reaching a local maximum, and then drastically decreases on approaching random close packing. Similar non-trivial behaviours are observed in the particle velocity and number-density fluctuations around volume fractions at which the non-trivial behaviour of the hydrodynamic diffusion is observed. We explain these non-trivial behaviours as a consequence of particle contacts, which are related to the dominant mechanism of particle pairings. The particle contacts are classified into attractive and repulsive classes by the nature of contacts, and in particular, the strong repulsive contact becomes predominant at $\unicode[STIX]{x1D719}>20\,\%$. Moreover, this transition is visible in the pair distribution functions, which also reveal the change in the suspension microstructure in concentrated regimes. It appears that strong and massive repulsive contacts along the direction perpendicular to an electric field promote the non-trivial suspension behaviours observed in concentrated regimes.

scholarly journals Tunable discontinuous shear thickening with magnetorheological suspensions

2017 ◽  
Vol 29 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Georges Bossis ◽  
Yan Grasselli ◽  
Alain Meunier ◽  
Olga Volkova
Keyword(s):  
Constant Velocity ◽  
Magnetic Particles ◽  
Shear Thickening ◽  
Magnetic Powder ◽  
Concentrated Suspensions ◽  
Abrupt Transition ◽  
Magnetorheological Suspensions ◽  
Solid Friction ◽  
Very High ◽  
Jammed State

Discontinuous shear thickening is a phenomenon observed in concentrated suspensions where, at a given applied stress, the flow becomes suddenly partially blocked and the shear rate begins to decrease and to oscillate when the stress is increased above the critical one. In this work, we show that it is possible to control with a magnetic field this abrupt transition from a flowing state to a jammed state, using a suspension of magnetic particles coated with a superplastifier molecule. In the case of experiments made at constant velocity, the transition to the jammed state corresponds to a very high jump of stress which can reach several hundred pascals for fields as low as a few kiloampere per meter. We present also results obtained in microgravity on a magnetic powder, showing that the solid friction between particles plays a key role in the jamming phenomenon.

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