Experiments and long-term high-performance computations on amplitude modulations of strato-rotational flows

Meletti, G.; Abide, Stéphane; Viazzo, Stéphane; Krebs, Andreas; Harlander, Uwe

doi:10.1080/03091929.2020.1795647

Cited by 6 publications

(22 citation statements)

References 34 publications

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“…2016), as well as in experiments using temperature stratification with oil and quite larger radius ratio and aspect ratio (Meletti et al. 2021). This suggests that the Prandtl number (which varies from approximately 700 for salt stratification, approximately 57 for the oil, to approximately 6 for temperature stratification in water) does not play a critical role in the layering pattern selection process.…”

Section: Three-dimensional Instability Of the Basic Statementioning

confidence: 96%

“…2017; Meletti et al. 2021). There are various advantages to using one or the other stratifying agent; Gellert & Rüdiger (2009) make a compelling case for using thermal stratification.…”

Section: Introductionmentioning

confidence: 99%

“…Also, either implicitly or explicitly, a centrifugal approximation is made whereby the angular acceleration is assumed to be negligibly small compared with gravitational acceleration (Meletti et al. 2021; Robins, Kersalé & Jones 2020). Shalybkov & Rüdiger (2005) discuss the possible importance of centrifugal buoyancy, particularly for strong stratification, but do not explore its consequences as ‘the situation becomes much more complicated’.…”

Section: Introductionmentioning

confidence: 99%

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Stratified Taylor–Couette flow: nonlinear dynamics

Lopez

Marqués

2021

J. Fluid Mech.

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A series of experiments on stratified Taylor–Couette flow in short aspect ratio wide-gap annuli found an intriguing and not-well-understood dynamics: nonlinear coherent structures appearing and disappearing periodically, along with density layering reminiscent of staircase profiles. A detailed numerical study is presented of the nonlinear dynamics near onset of instability in this setting, which explains most of the characteristics found in the experiments. The simulations show that centrifugal instability of the boundary layer on the inner rotating cylinder produces jets of angular momentum forming Taylor cells that are compressed axially due to the strong stratification. These cells are not axisymmetric from the onset, but are in fact two sets of Taylor cells displaced axially that meet in localized azimuthal defect regions where the cells are patched together; the whole structure is a rotating wave with azimuthal wavenumber $m=1$ . The presence of endwalls in this short aspect ratio annulus is critical for the understanding of the dynamics. Their impact cannot be accounted for in idealized axially periodic models. Another key ingredient is the role played by the symmetries of the system. Although the axial reflection symmetry is weakly broken by centrifugal buoyancy effects, following instability there are various branches of solutions corresponding to the different ways the system's symmetries may be broken.

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Section: Three-dimensional Instability Of the Basic Statementioning

confidence: 96%

“…2017; Meletti et al. 2021). There are various advantages to using one or the other stratifying agent; Gellert & Rüdiger (2009) make a compelling case for using thermal stratification.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stratified Taylor–Couette flow: nonlinear dynamics

Lopez

Marqués

2021

J. Fluid Mech.

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“…This problem is avoided when the stratification is accomplished via a stable vertical temperature gradient. Experiments and simulations using temperature stratification have been recently conducted [30,45], and some interesting nonlinear effects were reported at moderate values of Re. However, turbulence has so far not been observed in these cases either.…”

Section: Strato-rotational Instability In Centrifugally Stable Flowsmentioning

confidence: 99%

Stably stratified Taylor–Couette flows

Lopez

Marqués

2023

Phil. Trans. R. Soc. A.

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Stably stratified Taylor–Couette flow has attracted much attention due to its relevance as a canonical example of the interplay among rotation, stable stratification, shear and container boundaries, as well as its potential applications in geophysics and astrophysics. In this article, we review the current knowledge on this topic, highlight unanswered questions and propose directions for future research. This article is part of the theme issue ‘Taylor–Couette and related flows on the centennial of Taylor’s seminal Philosophical Transactions paper (part 2)’.

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“…The green dashed vertical line in the right represents the Keplerian line μ=η3/2. SRI unstable (circles) and stable (crosses) cases for η=0.517, Rn≈250, μ=0.35 with different Reynolds numbers were investigated numerically and experimentally in Meletti et al [12]. The circles filled with red colour refer to cases for which strong low-frequency amplitude modulations were observed.…”

Section: Introductionmentioning

confidence: 99%

A parameter study of strato-rotational low-frequency modulations: impacts on momentum transfer and energy distribution

Meletti

Abide

Viazzo

et al. 2023

Phil. Trans. R. Soc. A.

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Previous comparisons of experimental data with nonlinear numerical simulations of density stratified Taylor–Couette (TC) flows revealed nonlinear interactions of strato-rotational instability (SRI) modes that lead to periodic changes in the SRI spirals and their axial propagation. These pattern changes are associated with low-frequency velocity modulations that are related to the dynamics of two competing spiral wave modes propagating in opposite directions. In the present paper, a parameter study of the SRI is performed using direct numerical simulations to evaluate the influence of the Reynolds numbers, the stratification, and of the container geometry on these SRI low-frequency modulations and spiral pattern changes. The results of this parameter study show that the modulations can be considered as a secondary instability that are not observed for all SRI unstable regimes. The findings are of interest when the TC model is related to star formation processes in accretion discs. This article is part of the theme issue ‘Taylor–Couette and related flows on the centennial of Taylor’s seminal Philosophical Transactions paper (part 2)’.

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Experiments and long-term high-performance computations on amplitude modulations of strato-rotational flows

Cited by 6 publications

References 34 publications

Stratified Taylor–Couette flow: nonlinear dynamics

Stratified Taylor–Couette flow: nonlinear dynamics

Stably stratified Taylor–Couette flows

A parameter study of strato-rotational low-frequency modulations: impacts on momentum transfer and energy distribution

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