Multiplicity of states in Taylor-Couette flow of a dense granular gas

Molecular dynamics simulations with a purely repulsive Lennard-Jones potential and a normal damping force is used to simulate the granular flow in the annular region between two differentially-rotating cylinders, called the Taylor-Couette flow. The flow transition from the azimuthally-invariant Circular Couette flow (CCF) to the Taylor-vortex flow (TVF) is studied by increasing the rotation rate (ωi) of the inner cylinder, with the outer cylinder being kept stationary. Multiplicity of states, highlighting the hysteretic nature of the “CCF ↔ TVF” transition, is observed over a wide range of rotation rates. The onset of Taylor vortices is quantified in terms of the maximum radial velocity and the net circulation per vortex.

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Experimental Study of Axial Slit Wall Effect on Taylor-Couette Flow

Volume 2: Fora, Parts A and B ◽

10.1115/fedsm2007-37321 ◽

2007 ◽

Author(s):

Sang-Hyuk Lee ◽

Hyoung-Bum Kim

Keyword(s):

Reynolds Number ◽

Couette Flow ◽

Vortex Flow ◽

Outer Cylinder ◽

Velocity Fields ◽

Taylor Vortex ◽

Stable Mode ◽

Taylor Vortex Flow ◽

Taylor Couette ◽

Taylor Couette Flow

Taylor-Couette flow has been studied extensively and lots of variables which affect the flow instability are being reported. The wall geometry effect of Taylor-Couette flow, however, has been less studied. In this study, we investigated the effect of axial slit of outer cylinder. This kind of configuration can be easily seen in rotating machinery. Particle image velocimetry method was used to measure the velocity fields in longitudinal and latitudinal planes. The index matching method was used to avoid light refraction. The velocity fields between the slit and plain model which has the smooth wall were compared. From the experiments, both models have the same flow mode below Re = 143. The transition from circular Couette flow to plain Taylor vortex flow began at Re = 103, and the next transition to wavy vortex flow occurred at 124. The effect of slit wall appeared when the Reynolds number is larger than Re = 143. Above this Reynolds number, there was no stable mode and plain and wavy Taylor vortex flow randomly appeared.

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Effect of the number of vortices on the torque scaling in Taylor–Couette flow

Journal of Fluid Mechanics ◽

10.1017/jfm.2014.213 ◽

2014 ◽

Vol 748 ◽

pp. 756-767 ◽

Cited By ~ 31

Author(s):

B. Martínez-Arias ◽

J. Peixinho ◽

O. Crumeyrolle ◽

I. Mutabazi

Keyword(s):

Reynolds Number ◽

Aspect Ratio ◽

Couette Flow ◽

Scaling Laws ◽

Taylor Vortex ◽

Large Radius ◽

Aspect Ratios ◽

Taylor Vortex Flow ◽

Taylor Couette ◽

Taylor Couette Flow

AbstractTorque measurements in Taylor–Couette flow, with large radius ratio and large aspect ratio, over a range of velocities up to a Reynolds number of 24 000 are presented. Following a specific procedure, nine states with distinct numbers of vortices along the axis were found and the aspect ratios of the vortices were measured. The relationship between the speed and the torque for a given number of vortices is reported. In the turbulent Taylor vortex flow regime, at relatively high Reynolds number, a change in behaviour is observed corresponding to intersections of the torque–speed curves for different states. Before each intersection, the torque for a state with a larger number of vortices is higher. After each intersection, the torque for a state with a larger number of vortices is lower. The exponent, from the scaling laws of the torque, always depends on the aspect ratio of the vortices. When the Reynolds number is rescaled using the mean aspect ratio of the vortices, only a partial collapse of the exponent data is found.

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Effects of Shear Thinning on Taylor-Couette Flow: A Model for Synovial Fluid Flow

Volume 4: Fluid Structure Interaction, Parts A and B ◽

10.1115/pvp2006-icpvt-11-93379 ◽

2006 ◽

Author(s):

Nariman Ashrafi

Keyword(s):

Couette Flow ◽

Shear Thinning ◽

Taylor Number ◽

Taylor Vortex ◽

Narrow Gap ◽

Shear Thinning Fluids ◽

Wide Range ◽

Taylor Couette ◽

The Stability ◽

Taylor Couette Flow

The effect of shear thinning on the stability of the Taylor-Couette flow (TCF) is explored for a Carreau-Bird fluid in the narrow-gap limit to simulate journal bearings in general. Also considered is the changing eccentricity to cover a wide range of applied situations such as bearings and even articulation of human joints. Here, a low-order dynamical system is obtained from the conservation of mass and momentum equations. In comparison with the Newtonian system, the present equations include additional nonlinear coupling in the velocity components through the viscosity. It is found that the critical Taylor number, corresponding to the loss of stability of the base (Couette) flow becomes lower s the shear-thinning effect increases. Similar to Newtonian fluids, there is an exchange of stability between the Couette and Taylor vortex flows. However, unlike the Newtonian model, the Taylor vortex cellular structure loses its stability in turn as the Taylor number reaches a critical value. At this point, A Hopf bifurcation emerges, which exists only for shear-thinning fluids. Variation of stresses in the narrow gap has been evaluated with significant applications in the non-Newtonian lubricant.

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Hydromagnetic Taylor–Couette flow: wavy modes

Journal of Fluid Mechanics ◽

10.1017/s0022112002002409 ◽

2002 ◽

Vol 472 ◽

pp. 399-410 ◽

Cited By ~ 8

Author(s):

A. P. WILLIS ◽

C. F. BARENGHI

Keyword(s):

Magnetic Field ◽

Couette Flow ◽

Vortex Flow ◽

Axial Magnetic Field ◽

Taylor Vortex ◽

Taylor Vortex Flow ◽

Critical Reynolds Numbers ◽

Taylor Couette ◽

Axisymmetric Solutions ◽

Taylor Couette Flow

We investigate magnetic Taylor–Couette flow in the presence of an imposed axial magnetic field. First we calculate nonlinear steady axisymmetric solutions and determine how their strength depends on the applied magnetic field. Then we perturb these solutions to find the critical Reynolds numbers for the appearance of wavy modes, and the related wave speeds, at increasing magnetic field strength. We find that values of imposed magnetic field which alter only slightly the transition from circular-Couette flow to Taylor-vortex flow, can shift the transition from Taylor-vortex flow to wavy modes by a substantial amount. The results are compared to those for onset in the absence of a magnetic field.

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Experiments on the Stability of Taylor-Couette Flow With Different Radial Temperature Gradient

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C ◽

10.1115/fedsm-icnmm2010-30602 ◽

2010 ◽

Author(s):

Dong Liu ◽

Hyoung-Bum Kim

Keyword(s):

Reynolds Number ◽

Temperature Gradient ◽

Couette Flow ◽

Outer Cylinder ◽

Transition Process ◽

Taylor Vortex ◽

Radial Temperature ◽

Buoyant Force ◽

Taylor Couette ◽

Taylor Couette Flow

The effect of the temperature gradient and the presence of slits in the outer cylinders involved in creating a Taylor-Couette flow was investigated by measuring the velocity field inside the gap simultaneously. The slits were azimuthally located along the inner wall of outer cylinder and the number of slits was 18. The results showed that the buoyant force due to the temperature gradient clearly generated the helical flow when the rotating Reynolds number is small. For the plain model, the transition to turbulent Taylor vortex flow is not affected by the temperature gradient considered in this study. In addition, the transition process of 18-slit model was accelerated due to the slit wall. As the temperature gradient became larger, the critical Reynolds number of the transition process decreased.

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Bifurcation phenomena in Taylor–Couette flow with buoyancy effects

Journal of Fluid Mechanics ◽

10.1017/s0022112088003337 ◽

1988 ◽

Vol 197 ◽

pp. 479-501 ◽

Cited By ~ 29

Author(s):

K. S. Ball ◽

B. Farouk

Keyword(s):

Couette Flow ◽

Numerical Study ◽

Outer Cylinder ◽

Subsequent Development ◽

Buoyant Flows ◽

Annular Gap ◽

Bifurcation Phenomena ◽

Wide Range ◽

Taylor Couette ◽

Taylor Couette Flow

A numerical study has been conducted to determine the various modes of Taylor–Couette flow that exist between concentric vertical cylinders, as the aspect ratio Γ (height to gap width, H/d) and the Reynolds number Re (based on the inner cylinder speed) are varied. Furthermore, the effects of the introduction of buoyancy on the development of the flow are examined. This is accomplished by considering both cylinders to be isothermal, with the rotating inner cylinder at a higher temperature than the stationary outer cylinder. Results are presented for a wide range of the Grashof number Gr (based on the temperature difference ΔT across the annular gap). The structure of the Taylor vortices is observed to be distorted considerably with the buoyant flows, and the nature of the onset and subsequent development of the vortices is altered. The hysteresis between the different modes of cellular flow, characteristic of the bifurcation phenomena, is also substantially modified.

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Spatio-temporal character of non-wavy and wavy Taylor–Couette flow

Journal of Fluid Mechanics ◽

10.1017/s0022112098008969 ◽

1998 ◽

Vol 364 ◽

pp. 59-80 ◽

Cited By ~ 103

Author(s):

STEVEN T. WERELEY ◽

RICHARD M. LUEPTOW

Keyword(s):

Reynolds Number ◽

Couette Flow ◽

Vortex Flow ◽

Outer Cylinder ◽

Taylor Vortex ◽

Meridional Plane ◽

Azimuthal Wave ◽

Moderate Reynolds Number ◽

Taylor Couette ◽

Taylor Couette Flow

The stability of supercritical Couette flow has been studied extensively, but few measurements of the velocity field of flow have been made. Particle image velocimetry (PIV) was used to measure the axial and radial velocities in a meridional plane for non-wavy and wavy Taylor–Couette flow in the annulus between a rotating inner cylinder and a fixed outer cylinder with fixed end conditions. The experimental results for the Taylor vortex flow indicate that as the inner cylinder Reynolds number increases, the vortices become stronger and the outflow between pairs of vortices becomes increasingly jet-like. Wavy vortex flow is characterized by azimuthally wavy deformation of the vortices both axially and radially. The axial motion of the vortex centres decreases monotonically with increasing Reynolds number, but the radial motion of the vortex centres has a maximum at a moderate Reynolds number above that required for transition. Significant transfer of fluid between neighbouring vortices occurs in a cyclic fashion at certain points along an azimuthal wave, so that while one vortex grows in size, the two adjacent vortices become smaller, and vice versa. At other points in the azimuthal wave, there is an azimuthally local net axial flow in which fluid winds around the vortices with a sense corresponding to the axial deformation of the wavy vortex tube. These measurements also confirm that the shift-and-reflect symmetry used in computational studies of wavy vortex flow is a valid approach.

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Taylor-Couette flow with mixed convection heat transfer and variable properties in a horizontal annular pipe

Thermal Science ◽

10.2298/tsci210218271c ◽

2021 ◽

pp. 271-271

Author(s):

Ismahane Chaieb ◽

Toufik Boufendi ◽

Xavier Nicolas

Keyword(s):

Heat Transfer ◽

Physical Properties ◽

Couette Flow ◽

Outer Cylinder ◽

Convection Heat Transfer ◽

Numerical Code ◽

Taylor Vortex ◽

Aspect Ratios ◽

Taylor Couette ◽

Taylor Couette Flow

Taylor-Couette flows in a horizontal annular gap between finite coaxial cylinders in rotor-stator configuration are numerically investigated. The inner cylinder (rotor) rotates at a constant angular velocity while the outer cylinder (stator) is at rest. They are limited at their extremities by two fixed walls that prevent axial fluid flow. In addition, a heat transfer is generated by an imposed temperature difference, with the rotor hotter than the stator while the end-walls are adiabatic. The fluid physical properties are temperature dependent. This non-linear physics problem, with a strong coupling of the conservation equations and boundary conditions, is solved by a finite volume method with numerical schemes of second order space and time accuracies. The radius and aspect ratios and the Taylor, Grashof and Prandt numbers are the control parameters. The developed numerical code has been tested for different meshes and perfectly validated. Extensive calculations have been made in large ranges of the Taylor and Grashof numbers to analyze the Taylor-Couette flow in convection modes. The results highlight the dynamic and thermal instabilities generated in the Taylor Couette flow from the appearance of Ekman cells to the Taylor vortex propagation in the entire annulus. The combined effect of these vortices with the secondary flow improves the heat transfer. Furthermore, the influence of the physical properties in the radial direction is more marked in the vicinity of the walls. Finally, we propose an empirical correlation of the Nusselt number in the studied parameter ranges.

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FENOMENA ALIRAN TAYLOR COUETTE POISEUILLE DENGAN ALIRAN AKSIAL-RADIAL DI DALAM SILINDER KONSENTRIS

Jurnal Muara Sains, Teknologi, Kedokteran dan Ilmu Kesehatan ◽

10.24912/jmstkik.v5i1.9058 ◽

2021 ◽

Vol 5 (1) ◽

pp. 145

Author(s):

Sarip Sarip

Keyword(s):

Couette Flow ◽

Poiseuille Flow ◽

Radial Flow ◽

Outer Cylinder ◽

Taylor Vortex ◽

Digital Cameras ◽

Concentric Cylinders ◽

Flow Phenomena ◽

Taylor Couette ◽

Taylor Couette Flow

The filtering process using membrane technology is a modification of Taylor-Couette flow, which is a flow between two concentric cylinders that rotates with axial and radial flow and utilizes the vortex that occurs in Taylor-Couette flow which can increase membrane efficiency. The purpose this study was to determine the phenomenon of the Taylor Couette Poiseuille flow with axial-radial flow in concentric cylinders. The study was usesd a test section in the form of two concentric cylinders, in which the inner cylinder rotates as a membrane while the outer cylinder is stationary with a height of 500 mm, a radius ratio of 0.72; aspect ratio 40 and cylinder gap 12.5 mm. The inner cylinder rotation is set using an inverter to get the expected rotation. The phenomenon of observing flow patterns is done by using digital cameras on different inner cylinder turns. The results showed that changes in the inner cylinder rotations affect the flow pattern of Taylor-Couette that is formed in stages, namely laminar Couette, Taylor-vortex which is characterized by the appearance of paired vortexes, opposite directions that occur along the flow, wavy vortex and turbulant vortex. Changes in membrane porousity also show the effect of Taylor Couette Poiseuille flow phenomena with axial-radial flow which is higher, the transition to vortex occurs at higher Taylor numbers also means that Couette-Poiseuille flow stability increased. Keywords: axial-radial flow; Concentris cylinders; Taylor-Couette flow phenomenon. AbstrakProses penyaringan yang menggunakan teknologi membran merupakan modifikasi dari aliran Taylor-Couette, yaitu aliran diantara dua buah silinder konsentris yang berputar dengan aliran aksial dan radial serta memanfaatkan vortex yang terjadi pada aliran Taylor-Couette yang dapat meningkatkan efisiensi membran. Tujuan penelitian dilakukan untuk mengetahui fenomena aliran Taylor Couette Poiseuille dengan aliran aksial-radial di dalam silinder konsentris. Penelitian menggunakan seksi uji berupa dua silinder konsentris, yang mana silinder bagian dalam berputar sebagai membran sedangkan silinder luar diam dengan tinggi 500 mm, perbandingan radius 0,72; perbandingan aspek 40 dan celah silinder 12,5 mm. Putaran silinder bagian dalam diatur menggunakan inverter untuk mendapatkan putaran yang diharapkan. Fenomena pengamatan pola aliran dilakukan dengan menggunakan camera digital pada putaran silinder bagian dalam yang berbeda-beda. Hasil penelitian menunjukkan bahwa perubahan putaran silinder bagian dalam mempengaruhi pola aliran Taylor-Couette yang terbentuk secara berjenjang yaitu Couette laminar, Taylor-vortex yang ditandai dengan munculnya vortex yang saling berpasangan, berlawanan arah yang terjadi di sepanjang aliran, wavy vortex dan vortex turbulant. Perubahan porousitas membran juga menunjukkan pengaruh fenomena aliran Taylor Couette Poiseuille dengan aliran aksial-radial yang semakin tinggi maka transisi terjadinya vortex terjadi pada bilangan Taylor yang lebih tinggi pula berarti stabilitas aliran Couette-Poiseuille meningkat.

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