Wavy Taylor Vortex Research Articles

Counter-rotating suspension Taylor–Couette flow: pattern transition, flow multiplicity and the spectral evolution

Inertial transitions in a suspension Taylor–Couette flow are explored for the first time via experiments in the counter-rotation regime (i.e. the rotation ratio $\varOmega =\omega _o/\omega _i<0$ , where $\omega _i$ and $\omega _o$ are the angular speeds of the inner and outer cylinders, respectively) up to a particle volume fraction $\phi \leq 0.2$ . The primary bifurcation from the circular Couette flow (CCF) is found to yield patterns similar to those in a particle-free Newtonian fluid, and is supercritical at $|\varOmega |\leq 0.5$ but becomes hysteretic at large $|\varOmega |=1$ . It is shown that the states with different numbers of vortices can coexist over a large range of shear Reynolds number $\mbox {Re}_s(\phi )$ , confirming multi-stable behaviour of the primary and higher-order states for any particle loading at $|\varOmega |\leq 0.5$ . A quasi-periodic state characterized by two incommensurate frequencies, namely, the modulated wavy vortices (MWV), is found at $\varOmega =-0.5$ as a tertiary bifurcation from the wavy Taylor vortices (WTV), with the stationary Taylor vortex flow (TVF) being the primary bifurcating state from CCF at $\phi \geq 0$ . A novel sequence of transitions ${\rm TVF}\to {\rm MWV}_1\to {\rm WTV}\to {\rm MWV}$ , with another variant of modulated vortices (MWV $_1$ ) appearing directly from TVF as a secondary bifurcation, may also occur even for the particle-free ( $\phi =0$ ) case; the coexistence/non-uniqueness of WTV and MWV states is demonstrated over a range of $\mbox {Re}_s$ values spanning the secondary and tertiary bifurcation loci. At $\varOmega =-1$ , the primary bifurcation yields an oscillatory state (spiral/helical vortex flow) that gives birth to another oscillatory state (interpenetrating spiral vortices) and a non-periodic state (non-propagating interpenetrating spirals, NIS) as secondary and tertiary bifurcations, respectively, with NIS being characterized by the absence of frequency peaks in the power spectrum of the scattered light intensity. For all transitions at $\varOmega < 0$ , the critical values of $\mbox {Re}_s^c(\phi )$ decrease with increasing $\phi$ , with more destabilizing effects of particles being found at larger $|\varOmega |$ . The effect of particle loading is found to (i) decrease the amplitude and (ii) increase the wavelength of wavy vortices, with the latter seeming to be responsible for the decreased propagation frequencies of azimuthal waves with increasing $\phi$ . The normalized rotation frequency of spiral vortices also decreases with increasing $\mbox {Re}_s$ and $\phi$ , and a scaling relation in terms of the relative viscosity is found to collapse the frequency data for all $\phi$ .

Bubbles injection effect on Taylor–Couette flow controlled by deformations of inner cylinder cross-section

A numerical simulation is carried out to make investigation of bubbles interactions when injected in Taylor–Couette system. This process can affect the flow patterns, especially when it is combined with inner cylinder cross-section oscillations. The included phase is modeled by the Lagrangian approach. The flow regime range is considered until the onset of the wavy Taylor vortex flow (low regime). We attempt to characterize bubbles dispersion effects on the drag force near the inner-cylinder while it is executing radial sinusoidal deformations. It is assumed that the obtained configurations of air-bubbles accumulations are compared for validation with experimental and numerical studies from the literature. The bubbles have uniform spherical shape with a diameter Db = 0.06d, where d is the system gap width. The inner cylinder oscillation is imposed using a sinusoidal law with a fixed deforming frequency and different amplitude ratios of the initial radius R1. Overall, without reaching a fully developed regime, the obtained results for a low Taylor number showed that the drag reduction ratio could be decreased when the inner cylinder is deformed.

Statistics, plumes and azimuthally travelling waves in ultimate Taylor–Couette turbulent vortices

In this paper, we experimentally study the influence of large-scale Taylor rolls on the small-scale statistics and the flow organization in fully turbulent Taylor–Couette flow for Reynolds numbers up to $Re_{S}=3\times 10^{5}$. The velocity field in the gap confined by coaxial and independently rotating cylinders at a radius ratio of $\unicode[STIX]{x1D702}=0.714$ is measured using planar particle image velocimetry in horizontal planes at different cylinder heights. Flow regions with and without prominent Taylor vortices are compared. We show that the local angular momentum transport (expressed in terms of a Nusselt number) mainly takes place in the regions of the vortex in- and outflow, where the radial and azimuthal velocity components are highly correlated. The efficient momentum transfer is reflected in intermittent bursts, which becomes visible in the exponential tails of the probability density functions of the local Nusselt number. In addition, by calculating azimuthal energy co-spectra, small-scale plumes are revealed to be the underlying structure of these bursts. These flow features are very similar to the one observed in Rayleigh–Bénard convection, which emphasizes the analogies of these systems. By performing a complex proper orthogonal decomposition, we remarkably detect azimuthally travelling waves superimposed on the turbulent Taylor vortices, not only in the classical but also in the ultimate regime. This very large-scale flow pattern, which is most pronounced at the axial location of the vortex centre, is similar to the well-known wavy Taylor vortex flow, which has comparable wave speeds, but much larger azimuthal wavenumbers.

Suspension Taylor–Couette flow: co-existence of stationary and travelling waves, and the characteristics of Taylor vortices and spirals

Flow visualization and particle image velocimetry (PIV) measurements are used to unravel the pattern transition and velocity field in the Taylor–Couette flow (TCF) of neutrally buoyant non-Brownian spheres immersed in a Newtonian fluid. With increasing Reynolds number ($Re$) or the rotation rate of the inner cylinder, the bifurcation sequence in suspension TCF remains same as in its Newtonian counterpart (i.e. from the circular Couette flow (CCF) to stationary Taylor vortex flow (TVF) and then to travelling wavy Taylor vortices (WTV) with increasing $Re$) for small particle volume fractions ($\unicode[STIX]{x1D719}<0.05$). However, at $\unicode[STIX]{x1D719}\geqslant 0.05$, non-axisymmetric patterns such as (i) the spiral vortex flow (SVF) and (ii) two mixed or co-existing states of stationary (TVF, axisymmetric) and travelling (WTV or SVF, non-axisymmetric) waves, namely (iia) the ‘TVF$+$WTV’ and (iib) the ‘TVF$+$SVF’ states, are found, with the former as a primary bifurcation from CCF. While the SVF state appears both in the ramp-up and ramp-down experiments as in the work of Majji et al. (J. Fluid Mech., vol. 835, 2018, pp. 936–969), new co-existing patterns are found only during the ramp-up protocol. The secondary bifurcation TVF $\leftrightarrow$ WTV is found to be hysteretic or sub-critical for $\unicode[STIX]{x1D719}\geqslant 0.1$. In general, there is a reduction in the value of the critical Reynolds number, i.e. $Re_{c}(\unicode[STIX]{x1D719}\neq 0)<Re_{c}(\unicode[STIX]{x1D719}=0)$, for both primary and secondary transitions. The wave speeds of both travelling waves (WTV and SVF) are approximately half of the rotational velocity of the inner cylinder, with negligible dependence on $\unicode[STIX]{x1D719}$. The analysis of the radial–axial velocity field reveals that the Taylor vortices in a suspension are asymmetric and become increasingly anharmonic, with enhanced radial transport, with increasing particle loading. Instantaneous streamline patterns on the axial–radial plane confirm that the stationary Taylor vortices can indeed co-exist either with axially propagating spiral vortices or azimuthally propagating wavy Taylor vortices – their long-time stability is demonstrated. It is shown that the azimuthal velocity is considerably altered for $\unicode[STIX]{x1D719}\geqslant 0.05$, resembling shear-band type profiles, even in the CCF regime (i.e. at sub-critical Reynolds numbers) of suspension TCF; its possible role on the genesis of observed patterns as well as on the torque scaling is discussed.

Numerical Analysis of Critical Reynolds Number of Wavy Taylor Vortex Flow with Changing Aspect Ratio

Taylor vortex flow is one of the important vortex flows that have been studied since its classic study made by G. I. Taylor in 1923. State of the flow between inner and outer cylinders of a rotating co-axial cylinder transits from Couette flow to Taylor vortex flow and to wavy Taylor vortex flow as the increase of Reynolds number. This study has identified the critical Reynolds number when the flow changes from Taylor vortex flow to wavy Taylor vortex flow. The numerical analysis making use of the attractor in the chaos theory has been used in this identification of the critical Reynolds number. The calculated critical Reynolds numbers of each flow mode are almost identical to the values obtained by the visualization experiment at small aspect ratios. In the region where the aspect ratio is larger than the ratio at the peak critical Reynolds number, the distribution of the Reynolds number is qualitatively similar between the calculated and experimental values.

Modal switching of bubbly Taylor–Couette flow investigated by particle tracking velocimetry

Injection of bubbles into Taylor–Couette flow creates new flow modes which have not been experienced in single-phase flow conditions. An array of spiral vortices array is one such mode departing from the original toroidal Taylor vortices. The aim of the present study is to explore the mode transition of the two-phase flow using particle tracking velocimetry. Vertical-axis concentric cylinder with a rotating inner cylinder was used to measure the motion of both phases in the range 600 < Re < 4500. From time–space mapping of the experimentally measured stream functions, we found that bubble injection intensified the axial displacement of the wavy Taylor vortices in the toroidal array, and there was a smooth switching to a spiral array when the azimuthal traveling velocities coincided between two phases. During this vortical reconnection, the two counter-rotating vortices were attenuated asymmetrically. After the two phases co-organized a spiral array, the spiral-maintaining mechanism was weakened to restore the toroidal vortices. These forward and backward mode transitions occurred periodically as bubble injection flow rates increased. We, therefore, concluded that modal switching was an evidence of two-way bubble–vortex interaction for a maximized state, causing the largest drag reduction reported in this regime.

Linear stability analysis of the flow between rotating cylinders of wide gap

This study investigated by an analytical method the flow that develops in the gap between concentric rotating cylinders when the Taylor number Ta exceeds the first critical value. Concentric cylinders rotating at the speed ratio μ=0 are investigated over the radius ratio range 0.20≤η≤0.95. This range includes configurations characterised by a larger annular gap width d than classical journal bearing test cases and by a Taylor number beyond the first critical Taylor number at which Taylor vortices develop. The analysis focuses on determining the parameters for the direct transition from axisymmetric Couette flow to wavy Taylor vortex flow. The results show a marked change in trend as the radius ratio η reduces below 0.49 and 0.63 for the azimuthal wave-numbers m=2 and 3 respectively. The axial wavenumber increases so that the resulting wavy Taylor vortex flow is characterised by vortex structures elongated in the radial direction, with a meridional cross-section that is significantly elliptical. The linear stability analysis of the perturbation equations suggests this instability pattern is neutrally stable. Whereas a direct transition from axisymmetric Couette flow is not necessarily the only route for the onset of wavy Taylor vortex flow, the significant difference between the predicted pattern at large gap widths and classical wavy Taylor vortex flow merits further investigation.

Inertial flow transitions of a suspension in Taylor–Couette geometry

Experiments on the inertial flow transitions of a particle–fluid suspension in the concentric cylinder (Taylor–Couette) flow with rotating inner cylinder and stationary outer cylinder are reported. The radius ratio of the apparatus was $\unicode[STIX]{x1D702}=d_{i}/d_{o}=0.877$, where $d_{i}$ and $d_{o}$ are the diameters of inner and outer cylinders. The ratio of the axial length to the radial gap of the annulus $\unicode[STIX]{x1D6E4}=L/\unicode[STIX]{x1D6FF}=20.5$, where $\unicode[STIX]{x1D6FF}=(d_{o}-d_{i})/2$. The suspensions are formed of non-Brownian particles of equal density to the suspending fluid, of two sizes such that the ratio of annular gap to the mean particle diameter $d_{p}$ was either $\unicode[STIX]{x1D6FC}=\unicode[STIX]{x1D6FF}/d_{p}=30$ or $100$. For the experiments with $\unicode[STIX]{x1D6FC}=100$, the particle volume fraction was $\unicode[STIX]{x1D719}=0.10$ and for the experiments with $\unicode[STIX]{x1D6FC}=30$, $\unicode[STIX]{x1D719}$ was varied over $0\leqslant \unicode[STIX]{x1D719}\leqslant 0.30$. The focus of the work is on determining the influence of particle loading and size on inertial flow transitions. The primary effects of the particles were a reduction of the maximum Reynolds number for the circular Couette flow (CCF) and several non-axisymmetric flow states not seen for a pure fluid with only inner cylinder rotation; here the Reynolds number is $Re=\unicode[STIX]{x1D6FF}d_{i}\unicode[STIX]{x1D6FA}\unicode[STIX]{x1D70C}/2\unicode[STIX]{x1D707}_{s}$, where $\unicode[STIX]{x1D6FA}$ is the rotation rate of the inner cylinder and $\unicode[STIX]{x1D70C}$ and $\unicode[STIX]{x1D707}_{s}$ are the density and effective viscosity of the suspension. For purposes of maintaining uniform particle distribution, the rotation rate of the inner cylinder (or $Re$) was decreased slowly from a state other than CCF to probe the transitions. When $Re$ was decreased, pure fluid transitions from wavy Taylor vortex flow (WTV) to Taylor vortex flow (TVF) to CCF occurred. The suspension transitions differed. For $\unicode[STIX]{x1D6FC}=30$ and $0.05\leqslant \unicode[STIX]{x1D719}\leqslant 0.15$, with reduction of $Re$, additional non-axisymmetric flow states, namely spiral vortex flow (SVF) and ribbons (RIB), were observed between TVF and CCF. At $\unicode[STIX]{x1D719}=0.30$, the flow transitions observed were only non-axisymmetric: from wavy spiral vortices (WSV) to SVF to CCF. The values of $Re$ corresponding to each flow transition were observed to reduce with increase in particle loading for $0\leqslant \unicode[STIX]{x1D719}\leqslant 0.30$, with the initial transition away from CCF, for example, occurring at $Re\approx 120$ for the pure fluid and $Re\approx 75$ for the $\unicode[STIX]{x1D719}=0.30$ suspension. When the particle size was reduced to yield $\unicode[STIX]{x1D6FC}=100$, at $\unicode[STIX]{x1D719}=0.10$, only the RIB (and no SVF) was observed between TVF and CCF.

Axial slit wall effect on the flow instability and heat transfer in rotating concentric cylinders

The slit wall effect on the flow instability and heat transfer characteristics in Taylor-Couette flow was numerically studied by changing the rotating Reynolds number and applying the negative temperature gradient. The concentric cylinders with slit wall are seen in many rotating machineries. Six different models with the slit number 0, 6, 9, 12, 15 and 18 were investigated in this study. The results show the axial slit wall enhances the Taylor vortex flow and suppresses the azimuthal variation of wavy Taylor vortex flow. When negative temperature gradient exists, the results show that the heat transfer augmentation appears from laminar Taylor vortex to turbulent Taylor flow regime. The heat transfer enhancement become stronger as increasing the Reynolds number and slit number. The larger slit number model also accelerates the flow transition regardless of the negative temperature gradient or isothermal condition.

Wavy Taylor vortices in molecular dynamics simulation of cylindrical Couette flow.

Molecular dynamics simulations of flow between concentric rotating cylinders are performed. As the relative speed between the two cylinders is increased, a spontaneous flow bifurcation occurs and vortices form in a stationary-vortex or traveling-wavy-vortex configuration. The former emerges when the axial boundary conditions constrain the flow by reflection, and the traveling-wavy-vortex flow develops when the axial boundaries are relaxed to periodic conditions. The flow bifurcation is triggered by the thermal fluctuations in the system, and the resulting flow field is in agreement with previous experimental observations. In addition, the temporal growth of the Fourier mode that characterizes the wavy-vortex motion is well described by Landau's theory for Hopf bifurcations. The spatiotemporal energy spectrum is evaluated in order to characterize the instability in terms of its azimuthal wave number and wave speed.

Direct numerical simulation of Taylor-Couette flow subjected to a radial temperature gradient

Direct numerical simulations have been performed to study the Taylor-Couette (TC) flow between two rotating, coaxial cylinders in the presence of a radial temperature gradient. Specifically, the influence of the buoyant force and the outer cylinder rotation on the turbulent TC flow system with the radius ratio η = 0.912 was examined. For the co-rotating TC flows with Rei (inner cylinder) =1000 and Reo (outer cylinder) =100, a transition pathway to highly turbulent flows is realized by increasing σ, a parameter signifying the ratio of buoyant to inertial force. This nonlinear flow transition involves four intriguing states that emerge in sequence as chaotic wavy vortex flow for σ = 0, wavy interpenetrating spiral flows for σ = 0.02 and 0.05, intermittent turbulent spirals for σ = 0.1 and 0.2, and turbulent spirals for σ = 0.4. Overall, the fluid motion changes from a centrifugally driven flow regime characterized by large-scale wavy Taylor vortices (TVs) to a buoyancy-dominated flow regime characterized by small-scale turbulent vortices. Commensurate changes in turbulence statistics and heat transfer are seen as a result of the weakening of large-scale TV circulations and enhancement of turbulent motions. Additionally, the influence of variation of the outer cylinder rotation, −500 &amp;lt; Reo &amp;lt; 500 in presence of buoyancy (σ = 0.1) with Rei = 1000, has been considered. Specifically, it is demonstrated that this variation strongly influences the azimuthal and axial mean flows with a weaker influence on the fluctuating fluid motions. Of special interest, here are the turbulent dynamics near the outer wall where a marked decrease of turbulence intensity and a sign inversion of the Reynolds stress Rrz are observed for the strongly counter-rotating regimes (Reo = − 300 and −500). To this end, it has been shown that the underlying flow physics for this drastic modification are associated with the modification of the correlation between the radial and axial fluctuating motions. In turn, the intriguing effects of this modification on the mean axial flow, turbulent statistics, force balance, and dynamic processes such as turbulence production and dissipation are discussed.

The Persistence of Vortex Structures Between Rotating Cylinders in the 106 Taylor Number Range

The flow in the annular gap d = Ro - Ri between a stationary outer cylinder of radius Ro and a co-axial rotating inner cylinder of radius Ri is characterised at large gap, over the radius ratio (η) range 0.44 ≤ η ≤ 0.53 and aspect ratio (Γ) range 7.81 ≤ Γ ≤ 11.36. These configurations are more representative of turbomachinery bearing chambers and large rotating machinery than the journal bearing geometries of narrow gap commonly reported in the literature. Particle Image Velocimetry measurements are taken across the full meridional plane over the Taylor number (Ta) range 258 × 10 3 ≤ Ta ≤ 10.93 × 10 6 , which is 1000 times higher than the critical Taylor number for the onset of the first axisymmetric Taylor instability. Well-defined azimuthal vortex structures persist over this high Taylor number range, characterised by a constant number of vortices at a given aspect ratio, vortex core axial and radial motion over time, and mixing between neighbour vortices. This regime, with wavy Taylor vortex flow like features, is defined over the range 1.18 × 10 6 ≤ Ta ≤ 6.47 × 10 6 . These results form a body of experimental evidence from which further progress in the understanding of the wavy Taylor vortex dynamics can be sought, through advanced flow dynamic models that reproduce the persistence of the observed flow features.

Intensified and attenuated waves in a microbubble Taylor–Couette flow

The effect of the presence of microbubbles on a flow state is experimentally investigated in a Taylor–Couette flow with azimuthal waves, in order to examine the interaction mechanism of bubbles and flows that result in drag reduction. The average diameter of the bubbles is 60 μm, which is smaller than the Kolmogorov length scale, and the maximum void fraction is 1.2 × 10−4 at the maximum case. The modifications of the fluid properties, bulk density, effective viscosity, and the extra energy input caused by the addition of microbubbles are expected to have a small effect on modifying flow states. The power of the basic wave propagating in the azimuthal direction is enhanced; its modulation, however, is decreased by adding microbubbles in the flow regime corresponding to modulated Taylor vortex flow. Moreover, the gradient of the azimuthal velocity near the walls, source of the wall shear stress, decreases by 10%. The modified velocity distribution by adding microbubbles is comparable to that obtained with a 20% lower Reynolds number. Microbubbles in the coherent structure of the wavy Taylor vortices are visualized and exhibit a preferential distribution and motion at the crests and troughs of the waviness. The roles of the inhomogeneously distributed microbubbles in wavy vortical structures are discussed in view of our findings.

Localized modulation of rotating waves in Taylor-Couette flow

We report the results of an experimental study on the multiplicity of states in Taylor-Couette flow as a result of axial localization of azimuthally rotating waves. Localized states have been found to appear hysteretically from time-dependent Taylor-Couette flow at Reynolds numbers significantly above the onset of wavy Taylor vortices. These localized states have the shape of a modulated rotating wave and differ significantly from global modulated wavy Taylor vortex states in their spatial characteristics. Axial localization of rotating waves is accompanied with a significant increase in size of the underlying pair of Taylor vortices. Our work reveals that localization provides a mechanism for the appearance of multiple time-dependent states in Taylor-Couette flow.

Influence of homogeneous magnetic fields on the flow of a ferrofluid in the Taylor-Couette system

We investigate numerically the influence of a homogeneous magnetic field on a ferrofluid in the gap between two concentric, independently rotating cylinders. The full Navier-Stokes equations are solved with a combination of a finite difference method and a Galerkin method. Structure, dynamics, symmetry properties, bifurcation, and stability behavior of different vortex structures are investigated for axial and transversal magnetic fields, as well as combinations of them. We show that a transversal magnetic field modulates the Taylor vortex flow and the spiral vortex flow. Thus, a transversal magnetic field induces wavy structures: wavy Taylor vortex flow (wTVF) and wavy spiral vortex flow. In contrast to the classic wTVF, which is a secondarily bifurcating structure, these magnetically generated wavy Taylor vortices are pinned by the magnetic field, i.e., they are stationary and they appear via a primary forward bifurcation out of the basic state of circular Couette flow.

End wall effects on the transitions between Taylor vortices and spiral vortices

We present numerical simulations as well as experimental results concerning transitions between Taylor vortices and spiral vortices in the Taylor-Couette system with rigid, nonrotating lids at the cylinder ends. These transitions are performed by wavy structures appearing via a secondary bifurcation out of Taylor vortices and spirals, respectively. In the presence of these axial end walls, pure spiral solutions do not occur as for axially periodic boundary conditions but are substituted by primary bifurcating, stable wavy spiral structures. Similarly to the periodic system, we found a transition from Taylor vortices to wavy spirals mediated by so-called wavy Taylor vortices and, on the other hand, a transition from wavy spirals to Taylor vortices triggered by a propagating defect. We furthermore observed and investigated the primary bifurcation of wavy spirals out of the basic circular Couette flow with Ekman vortices at the cylinder ends.

Transitions between Taylor vortices and spirals via wavy Taylor vortices and wavy spirals

We present numerical simulations of closed wavy Taylor vortices and of helicoidal wavy spirals in the Taylor–Couette system. These wavy structures appearing via a secondary bifurcation out of Taylor vortex flow and out of spiral vortex flow, respectively, mediate transitions between Taylor and spiral vortices and vice versa. Structure, dynamics, stability and bifurcation behaviour are investigated in quantitative detail as a function of Reynolds numbers and wave numbers for counter-rotating as well as corotating cylinders. These results are obtained by solving the Navier–Stokes equations subject to axial periodicity for a radius ratio η=0.5 with a combination of a finite differences method and a Galerkin method.

Sludge Dewatering and Aggregate Formation Effects through Taylor Vortex Assisted Flocculation

For polymer induced flocculation processes, the effects of flow patterns in a gap of a conical stirrer on aggregate formation and subsequent sludge dewatering efficiency were analysed. Different flow regimes were identified by lab scale investigations with model substances and summarized in a Ta and Re number plane. An enhancement of sludge dewaterability for polymer induced flocculation processes was identified through post‐treatment of flocculated sludge aggregates by the specific flow pattern of stable and wavy Taylor vortices. Photo‐optical image analysis of flocculated aggregates shows a clear change of aggregate size distribution with less small particles during aggregate forming by Taylor vortices compared to classical flocculation procedure by stirrer. Results from technical scale dewatering analyses confirmed enhancement of sludge dewatering efficiency for six different dewatering machines using the identified wavy and stable Taylor vortex flow pattern regime.

축방향 홈이 있는 Taylor-Couette 유동의 실험적 연구

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.Copyright © 2007 by ASME

3936 アスペクト比が小さいテイラー渦流れの波動モードの決定に関する3次元数値計算(J08-2 流体情報学と発見科学(2),J08 流体情報学と発見科学)

We performed a 3-dimensional numerical computation of Taylor vortex flow at small aspect ratio. The critical Reynolds number at the onset of the wavy Taylor vortex is determined by using velocity vectors and variations of the energy of each cell. The numerical results were compared with experimental results, and they had the qualitative agreement.