Effect of shear-thinning behavior on flow regimes in Taylor–Couette flows

Elçiçek, Hüseyi̇n; Güzel, Bülent

doi:10.1016/j.jnnfm.2020.104277

Cited by 8 publications

(14 citation statements)

References 28 publications

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“…Sudden changes of the spiralling propagation direction may occur and give rise to a similar flow state called the interpenetrating spiral vortex flow (ISVF) (Baumert & Muller 1997; Ramesh & Alam 2020). In the recent works by Elçiçek & Güzel (2020 a , b ) SVF (sometimes coexisting with TVF) has also been observed in shear-thinning (possibly also elastic) XG solutions. Remarkably, SVF and ISVF have been found to coexist with RIB states under certain conditions (Ramesh & Alam 2020).…”

Section: Resultsmentioning

confidence: 89%

Shear-thinning mediation of elasto-inertial Taylor–Couette flow

2021

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Section: Resultsmentioning

confidence: 89%

Shear-thinning mediation of elasto-inertial Taylor–Couette flow

2021

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“…The value of at which these patterns appear decreases with increasing shear-thinning effects. Elçiçek & Güzel (2020) have also reported, from visualization experiments, the existence of axisymmetric vortices at (before TVF regime, figure 10 in their paper) and they attributed their existence to Eckman vortices.…”

Section: Primary Bifurcation: Onset Of Tvfmentioning

confidence: 89%

“…However, this result is limited only to a narrow annular space with a radius ratio . Recently, Elçiçek & Güzel (2020) suggested using an average Reynolds number , defined as an average over the annular space of the local Reynolds number calculated using the local velocity and the local viscosity. With this definition, it is observed that the critical Reynolds number increases with increasing shear-thinning effects.…”

Section: Introductionmentioning

confidence: 99%

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Secondary instabilities in Taylor–Couette flow of shear-thinning fluids

2021

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The stability of the Taylor vortex flow in Newtonian and shear-thinning fluids is investigated in the case of a wide gap Taylor–Couette system. The considered radius ratio is $\eta = R_1/R_2=0.4$ . The aspect ratio (length over the gap width) of experimental configuration is 32. Flow visualization and measurements of two-dimensional flow fields with particle image velocimetry are performed in a glycerol aqueous solution (Newtonian fluid) and in xanthan gum aqueous solutions (shear-thinning fluids). The experiments are accompanied by axisymmetric numerical simulations of Taylor–Couette flow in the same gap of a Newtonian and a purely viscous shear-thinning fluid described by the Carreau model. The experimentally observed critical Reynolds and wavenumbers at the onset of Taylor vortices are in very good agreement with that obtained from a linear theory assuming a purely viscous shear-thinning fluid and infinitely long cylinders. They are not affected by the viscoelasticity of the used fluids. For the Newtonian fluid, the Taylor vortex flow (TVF) regime is found to bifurcate into a wavy vortex flow with a high frequency and low amplitude of axial oscillations of the vortices at ${Re} = 5.28 \, {Re}_c$ . At ${Re} = 6.9 \, {Re}_c$ , the frequency of oscillations decreases and the amplitude increases abruptly. For the shear-thinning fluids the secondary instability conserves axisymmetry. The latter is characterized by an instability of the array of vortices leading to a continuous sequence of creation and merging of vortex pairs. Axisymmetric numerical simulations reproduce qualitatively very well the experimentally observed flow behaviour.

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“…Concerning the flow field and the form of the vortices, several authors found that in shear‐thinning fluids the following can be observed 48‐52 : The location of the vortex eye is radially shifted against the inner cylinder wall Shear‐thinning causes an increase in the axial wavelength of the Taylor‐vortex flow The vortices undergo an axial drift Escudier et al found that for non‐Newtonian fluids that are viscoelastic, the axial drift occurs in the direction opposite to the center body rotation vector 49 . Using a thixotropic fluid on the other hand caused an axial drift in the other direction.…”

Section: Fundamentals Of Taylor‐couette Flowmentioning

confidence: 99%

Taylor‐Couette reactor: Principles, design, and applications

et al. 2021

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The Taylor-Couette reactor (TCR) is an apparatus that capitalizes on the Taylor-Couette flow, which allows many flow regimes and conditions to perform (bio-)chemical conversions with precise control of various reactor characteristics. With the possibility to continuously perfuse the reactor with a reaction medium, the TCR becomes interesting for chemical engineering applications. In this review we introduce this reactor type and provide an overview of its history, principles of the flow regimes, and a description and design aspects of the reactors and their elements. Available information in the literature is summarized and harmonized to present available formulas and correlations in a consistent set of variables. Additionally, a wide number of applications in process technology is covered, including reactions in homogeneous, photo and enzymatic catalysis, polymer synthesis, and crystallization and aggregation-flocculation processes. Focusing on this reactor configuration, this article intends to be used as a hub for scientific groups interested in TCRs. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as

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Effect of shear-thinning behavior on flow regimes in Taylor–Couette flows

Cited by 8 publications

References 28 publications

Shear-thinning mediation of elasto-inertial Taylor–Couette flow

Shear-thinning mediation of elasto-inertial Taylor–Couette flow

Secondary instabilities in Taylor–Couette flow of shear-thinning fluids

Taylor‐Couette reactor: Principles, design, and applications

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