scholarly journals Empirical Modelling of Nonmonotonous Behaviour of Shear Viscosity

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
J. David ◽  
P. Filip ◽  
A. A. Kharlamov
Keyword(s):  
Shear Viscosity ◽  
Extreme Points ◽  
Shear Thickening ◽  
Local Maximum ◽  
Shear Thinning ◽  
Algebraic Form ◽  
Complex Behaviour ◽  
Empirical Modelling ◽  
Newtonian Liquids ◽  
Almost All

Almost all hitherto proposed empirical models used for characterization of shear viscosity of non-Newtonian liquids describe only its monotonous course. However, the onset of new materials is accompanied by more complicated characteristics of their behaviour including nonmonotonous course of shear viscosity. This feature is reflected not only in an existence of one extreme point (maximum or minimum), but also it can appear in both extreme points; that is, this shear viscosity initially exhibits shear thinning; after attaining a local minimum, it converts to shear thickening, and again after reaching a local maximum, it has a shear-thinning character. It is clear that, for an empirical description of this complex behaviour, a hitherto, used number of parameters (four, five) in classical monotonous models (such as Cross or Carreau-Yasuda) are no longer tenable. If more parameters are applied, there should be given an emphasis on a relatively simple algebraic form of the proposed models, unambiguity of the involved parameters, and their sound interpretation in the whole modelling. This contribution provides an overview of the existing empirical nonmonotonous models and proposes a new 10-parameter model including a demonstration of its flexibility using various experimental data.

The Instability of Shear Thinning and Shear Thickening Spiralling Liquid Jets: Linear Theory

2006 ◽  
Vol 128 (5) ◽  
pp. 968-975 ◽  
Author(s):  
J. Uddin ◽  
S. P. Decent ◽  
M. J. Simmons
Keyword(s):  
Asymptotic Methods ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Wave Mode ◽  
Linear Instability ◽  
Liquid Jets ◽  
Flow Index ◽  
Rotation Rates ◽  
Newtonian Liquids ◽  
Small Rotation

The linear instability of a power law liquid emerging as a jet from an orifice on the surface of a rotating container is investigated, with applications to industrial prilling. Asymptotic methods are used to examine the growth rate and wavenumber of the most unstable traveling wave mode for different flow index numbers. Comparison with Newtonian liquids show that for small rotation rates shear thinning liquids are most stable to disturbances. In contrast for higher rotation rates we find shear thickening liquids are more stable than shear thinning liquids. The influence of viscosity, surface tension, and rotation rate on the growth rates and most unstable wavenumbers associated with both types of liquids are also examined.

Influence of Temperature and Shear Rate on Rheological Properties of CTAC/NaSal Aqueous Solution

2019 ◽  
Vol 12 (4) ◽  
pp. 296-311
Author(s):  
Mingjun Pang ◽  
Chengcheng Xie
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Shear Viscosity ◽  
Chemical Engineering ◽  
Sodium Salicylate ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Power Law Function ◽  
Cetyltrimethyl Ammonium ◽  
Increasing Temperature

Background: It is very important for understanding the turbulence drag-reducing mechanism and for improving product quality in the fields of pharmaceutical and chemical engineering to deeply investigate the rheological properties of surfactants solutions. Methods: The rheological properties of Cationic surfactant (Cetyltrimethyl Ammonium Chloride)/Sodium salicylate were measured and analyzed with the MCR302 rheometer. Results: The present results show that the shear viscosity of CTAC/NaSal solution with the exception of 0.9375mmol·L-1 can show the Newtonian characteristic, the shear-thickening, the shear-thinning and the stable shear properties with changing shear time. The induction time increases with a shear rate as a power law function relation tind=aγb. Conclusion: The shear viscosity of the CTAC/NaSal solution can be divided into three regions with shear rate, and its flow curve conforms to a linear function in the logarithmic coordinate. When the concentration and the shear rate are relatively high, the viscosity curve of the CTAC/NaSal solution appears "platform" at the high temperature. When the shear rate is greater than 90s-1, the shear viscosity only appears shear thinning with increasing temperature.

Modelling steady shear flows of Newtonian liquids with non-Newtonian interfaces

2017 ◽  
Vol 814 ◽  
pp. 5-23 ◽  
Author(s):  
Patrick T. Underhill ◽  
Amir H. Hirsa ◽  
Juan M. Lopez
Keyword(s):  
Shear Viscosity ◽  
Packing Density ◽  
Stokes Equations ◽  
Shear Thinning ◽  
Steady Shear ◽  
Surface Shear ◽  
Bulk Fluid ◽  
Coupled Problem ◽  
Newtonian Liquids ◽  
Surface Shear Viscosity

In countless biological and technological processes, the flow of Newtonian liquids with a non-Newtonian interface is a common occurrence, such as in monomolecular films in ‘solid’ phases atop of aqueous bulk fluid. There is a lack of models that can predict the flow under conditions different from those used to measure the rheological response of the interface. Here, we present a model which describes interfacial hydrodynamics, including two-way coupling to a bulk Newtonian fluid described by the Navier–Stokes equations, that allows for shear-thinning response of the interface. The model includes a constitutive equation for the interface under steady shear that takes the Newtonian functional form but where the surface shear viscosity is generalized to be a function of the local shear rate. In the limit of a highly viscous interface, the interfacial hydrodynamics is decoupled from the bulk flow and the model can be solved analytically. This provides not only insight into the flow but also a means to validate the numerical technique for solving the two-way coupled problem. The numerical results of the coupled problem shed new light on existing experimental results on steadily sheared monolayers of dipalmitoylphosphatidylcholine (DPPC), the primary constituent of lung surfactant and the bilayers of mammalian cell walls. For low packing density DPPC monolayers, a Newtonian shear-independent surface shear viscosity model can reproduce the interfacial flows, but at high packing density, the shear-thinning properties of the new model presented here are needed.

Stability of Shear-Thickening Liquids Between Rotating Cylinders

2010 ◽  
Author(s):  
Nariman Ashrafi ◽  
Habib Karimi Haghighi
Keyword(s):  
Couette Flow ◽  
Dynamical Behavior ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Taylor Vortex ◽  
Shear Dependent Viscosity ◽  
Shear Thinning Fluids ◽  
Shear Thickening Fluids ◽  
The Stability ◽  
Dependent Viscosity

The effects of nonlinearities on the stability are explored for shear thickening fluids in the narrow-gap limit of the Taylor-Couette flow. It is assumed that shear-thickening fluids behave exactly as opposite of shear thinning ones. A dynamical system is obtained from the conservation of mass and momentum equations which include nonlinear terms in velocity components due to the shear-dependent viscosity. It is found that the critical Taylor number, corresponding to the loss of stability of Couette flow becomes higher as the shear-thickening effects increases. Similar to the shear thinning case, the Taylor vortex structure emerges in the shear thickening flow, however they quickly disappear thus bringing the flow back to the purely azimuthal flow. Naturally, one expects shear thickening fluids to result in inverse dynamical behavior of shear thinning fluids. This study proves that this is not the case for every point on the bifurcation diagram.

scholarly journals Rheological properties of hydroxypropylmethyl cellulose/sodium dodecylsulfate mixtures

2014 ◽  
Vol 79 (4) ◽  
pp. 457-468 ◽  
Author(s):  
Jaroslav Katona ◽  
Sandra Njaradi ◽  
Verica Sovilj ◽  
Lidija Petrovic ◽  
Brankica Marceta ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Sodium Dodecylsulfate ◽  
Shear Thinning ◽  
Cellulose Ether ◽  
Flow Profile ◽  
Hydroxypropylmethyl Cellulose ◽  
Shear Rates ◽  
Newtonian Liquids ◽  
Shear Induced Structure ◽  
Induced Structure

Rheological properties of mixtures of hydroxypropylmethyl cellulose (HPMC), a nonionic associative cellulose ether, and sodium dodecylsulfate (SDS), an anionic surfactant, were investigated by viscosity measurements performed at different shear rates (0.1-6000 s-1). HPMC/SDS mixtures containing different concentrations of SDS (CSDS=0.00-3.50 % w/w) and HPMC concentrations which corresponded to the overlap parameter c/c*=3, 6, and 12 were prepared. All HPMC/SDS mixtures were found to be shear-thinning when examined in a low-end-to mid-range of the applied shear rates. The degree of shear-thinning, n, and viscosity of the mixtures were influenced by composition of HPMC/SDS mixtures and HPMC-SDS complex formation. The changes in n ranged from values typical for highly shear thinning to almost perfectly Newtonian liquids, and were more pronounced as c/c* was increased from 3 to 6 and 12. A change in flow profile and a buildup of the first normal stress difference (N1) was observed in HPMC/SDS mixtures with c/c*=6 and 12 and CSDS 0.55-1.00 % and 0.55-2.50 %, respectively, when a critical shear rate, crit. was exceeded, suggesting that a shear-induced structure formation in the mixtures took place.

scholarly journals Surface shear inviscidity of soluble surfactants

2014 ◽  
Vol 111 (10) ◽  
pp. 3677-3682 ◽  
Author(s):  
Zachary A. Zell ◽  
Arash Nowbahar ◽  
Vincent Mansard ◽  
L. Gary Leal ◽  
Suraj S. Deshmukh ◽  
...  
Keyword(s):  
Shear Viscosity ◽  
Nonionic Surfactants ◽  
Emulsion Stability ◽  
Foam Stability ◽  
Sensitivity Limit ◽  
Multiple Control ◽  
Surface Shear ◽  
Soluble Surfactants ◽  
Almost All ◽  
Surface Shear Viscosity

Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 μN·s/m. This conflicts directly with almost all previous studies, which reported values up to 103–104 times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high- and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants.

scholarly journals The Effect of Rheology of Viscoelastic Polymer on Pressure Transient Response in Near-Wellbore Regions

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jia Zhang ◽  
Shiqing Cheng ◽  
Jie Zhan ◽  
Qi Han
Keyword(s):  
Shear Thickening ◽  
Shear Thinning ◽  
Polymer Flooding ◽  
High Shear ◽  
Pressure Data ◽  
Transient Pressure ◽  
Pressure Derivative ◽  
Shear Rates ◽  
Viscoelastic Polymer ◽  
Thickening Behavior

Viscoelastic polymer solution shows shear thinning behavior at low shear rates and shear thickening behavior at high shear rates in reservoirs. However, models that ignored shear thickening behavior were commonly employed to interpret transient pressure data derived from tested wells in viscoelastic polymer flooding systems; although, viscoelastic polymer solutions show shear thickening behavior in the near-wellbore region due to high shear rate. To better characterize the oilfield with pressure transient analysis in viscoelastic polymer flooding systems, we developed a numerical model that takes into account both shear thinning behavior and shear thickening behavior. A finite volume method was employed to discretize partially differential flow equations in a hybrid grid system including PEBI mesh and Cartesian grid, and the Newton-Raphson method was used to solve the fully implicit nonlinear system. To illustrate the significance of our model, we compared our model with a model that ignores the shear thickening behavior by graphing their solutions on log-log plots. In the flow regime of near-wellbore damage, the pressure derivative computed by our model is distinctly larger than that computed by the model ignoring shear thickening behavior. Furthermore, the effect of shear thickening behavior on pressure derivative differs from that of near-wellbore damage. We then investigated the influence of shear thickening behavior on pressure derivative with different polymer injection rates, injection rates, and permeabilities. The results can provide a benchmark to better estimate near-wellbore damage in viscoelastic polymer flooding systems. Besides, we demonstrated the applicability and accuracy of our model by interpreting transient pressure data from a field case in an oilfield with viscoelastic polymer flooding treatments.

Surface-tension-driven breakup of viscoelastic liquid threads

1982 ◽  
Vol 120 ◽  
pp. 245-266 ◽  
Author(s):  
Simon L. Goren ◽  
Moshe Gottlieb
Keyword(s):  
Relaxation Time ◽  
Stress Relaxation ◽  
Polymer Solutions ◽  
Small Diameter ◽  
Shear Thinning ◽  
Prior History ◽  
Axial Tension ◽  
Dilute Polymer Solutions ◽  
Linearized Stability ◽  
Newtonian Liquids

A linearized stability analysis is carried out for the breakup of small-diameter liquid filaments of dilute polymer solutions into droplets. Oldroyd's 8-constant model expressed in a corotational reference frame is used as the rheological equation of state. The crucial idea in this theory is the recognition that the liquid may be subject to an unrelaxed axial tension due to its prior history. If the tension is zero, the present analysis predicts that jets of shear-thinning liquids are less stable than comparable jets of Newtonian liquids; this is in agreement with previous analyses. However, when the axial tension is not zero, and provided the stress relaxation time constant is sufficiently large, the new theory predicts that the axial elastic tension can be a significant stabilizing influence. With reasonable values for the tension and stress relaxation time the theory explains the great stability observed for jets of some shear- thinning, dilute polymer solutions. The theory explains why drops produced from jets of such liquids are larger than drops from corresponding Newtonian liquids. The theory also appears capable of explaining the sudden appearance of irregularly spaced bulges on jets after long distances of t,ravel with little amplification of disturbances.

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