Lubricating Flow of Thixotropic Fluids in Slipper-Pad Bearing: A Numerical Study

Najmi, Kamyar; Karimzadeh, M.; Sadeghy, Kayvan

doi:10.1678/rheology.39.153

Cited by 5 publications

(8 citation statements)

References 17 publications

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“…This is the 'slow-adjusting' behaviour also described in section 2.4, and to leading order the structure parameter must be given by λ ∼ λ av (y), where λ av is defined by (14). Between these two regimes of behaviour is a marginal case, h = a, in which all three terms in (18) are of comparable magnitude and we may expect the behaviour to be intermediate between fast-and slowadjusting behaviour. We shall consider each case in turn.…”

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confidence: 76%

“…In contrast, the structural model used by Billingham & Ferguson [14] and by Derksen & Prashant [15], based on the original model by Moore [16], incorporates structure-dependent build-up. With some variations in the choice of constitutive relation, this model has recently been investigated in various geome-3 tries [17,18,19]. (Billingham & Ferguson [14] also incorporated a structure diffusion term, but this has been less widely adopted.)…”

Section: Introductionmentioning

confidence: 99%

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The Stokes boundary layer for a thixotropic or antithixotropic fluid

McArdle

Pritchard

Wilson

2012

Journal of Non-Newtonian Fluid Mechanics

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We present a mathematical investigation of the oscillatory boundary layer ('Stokes layer') in a semi-infinite fluid bounded by an oscillating wall (the socalled 'Stokes problem'), when the fluid has a thixotropic or antithixotropic rheology. We obtain asymptotic solutions in the limit of small-amplitude oscillations, and we use numerical integration to validate the asymptotic solutions and to explore the behaviour of the system for larger-amplitude oscillations. The solutions that we obtain differ significantly from the classical solution for a Newtonian fluid. In particular, for antithixotropic fluids the velocity reaches zero at a finite distance from the wall, in contrast to the exponential decay for a thixotropic or a Newtonian fluid.For small amplitudes of oscillation, three regimes of behaviour are possible: the structure parameter may take values defined instantaneously by the shear rate, or by a long-term average; or it may behave hysteretically. The regime boundaries depend on the precise specification of structure build-up * Corresponding author. E-mail: david.pritchard@strath.ac.uk. Tel.: (+44)(0)141 548 3819. Fax: (+44)(0)141 548 3345.Preprint submitted to Journal of Non-Newtonian Fluid Mechanics June 12, 2012 and breakdown rates in the rheological model, illustrating the subtleties of complex fluid models in non-rheometric settings. For larger amplitudes of oscillation the dominant behaviour is hysteretic. We discuss in particular the relationship between the shear stress and the shear rate at the oscillating wall.

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confidence: 76%

Section: Introductionmentioning

confidence: 99%

The Stokes boundary layer for a thixotropic or antithixotropic fluid

McArdle

Pritchard

Wilson

2012

Journal of Non-Newtonian Fluid Mechanics

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“…Among common thixotropic fluid systems, one can mention drilling muds, foodstuffs, paints, concretes, semi-solids, and physiological fluids. There are also a number of experimental and theoretical studies on the thixtropic fluid flows (Assad et al [3]; Wallevik [4]; Derksen & Prashant [5]; Ardakani et al [6] and Najmi et al [7]) that are published recently due to the important applications of these kinds of fluids in various industries.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Behaviour of Oscillating Bubbles inside a Nonlinear Thixotropic Fluid in Existence of Magnetic Field

Taklifi¹

2019

Proceedings of the 6th International Conference on Fluid Flow, Heat and Mass Transfer (FFHMT'19)

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Bubbles inside fluids respond to acoustically imposed pressure forces and reveal their full potential when periodically driven by sound waves. These bubbles oscillations could not be easily captured experimentally especially for high frequency excitations. The effect of an imposed magnetic field on nonlinear oscillations of acoustically forced spherical gas bubbles in a time-dependant viscosity fluid (thixotropic fluid) is investigated in this paper. These behaviours are of great interest as the bubbles should adapt their dynamical properties with a shear thinning surrounded medium with some lag time of reaction in addition to nonlinearities being imported due to the magnetic field force on the bubbles. For this study the basic governing equations of the bubbles oscillations has been modified to add the magnetic body force effects. The Moore's model is also used to model the Thixotropic properties of the medium and various structural parameters were considered to understand the dynamic behaviour of the bubbles. By using the RK4 method for numerical solution of the set of defined governing equations, the combined effects of structure build-up, structure breakdown and magnetic field on bubble radius variations are investigated. The results show that both the gas bubbles oscillation in thixotropic fluids and structural changes (viscosity changes) of these kinds of fluids could be effectively controlled by external magnetic fields. The relevance and importance of these bubble dynamics to biomedical ultrasound applications and light emissions by sonoluminescen and many other cement paste industries and etc. could be obviously addressed as the possible applications of this study.

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“…[4][5][6] In recent years more complex geometries such as boundary-layer fl ows, lubricating flows, and cavitation flows have also been investigated for thixotropic fluids. [7][8][9][10] Having said this, it should be conceded that the need still exists as to addressing the fl ow of thixotropic fl uids in more practical fl ow situations such as that encountered in peristaltic (say, roller) pumping.…”

Section: Introductionmentioning

confidence: 99%