A reverse transition route from inertial to elasticity-dominated turbulence in viscoelastic Taylor–Couette flow

Song, Jiaxing; Wan, Zhen-Hua; Liu, Nansheng; Lu, Xi‐Yun; Khomami, Bamin

doi:10.1017/jfm.2021.728

Cited by 14 publications

(27 citation statements)

References 55 publications

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“…In the simulations presented here, S c = 100, which yields an artificial diffusion coefficient, 1/ReS c = 10 −4 . This amount of diffusion is similar in magnitude to those used in other recent numerical studies on viscoelastic flows (Xi & Graham 2010;Lopez et al 2019;Song et al 2019;Zhu et al 2020;Song et al 2021b;Zhu et al 2022). It has been verified that a reduction in the amount of diffusion does not significantly alter the results of the simulations (Sc up to 200 were tested), thereby confirming the adequacy of the diffusion used for the simulations throughout the paper.…”

Section: Problem Formulation Dimensionless Parameters and Numerical M...supporting

confidence: 82%

Vortex merging and splitting events in viscoelastic Taylor–Couette flow

Lopez

2022

J. Fluid Mech.

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Recent experiments have reported a novel transition to elasto-inertial turbulence in the Taylor–Couette flow of a dilute polymer solution. Unlike previously reported transitions, this newly discovered scenario, dubbed vortex merging and splitting (VMS) transition, occurs in the centrifugally unstable regime and the mechanisms underlying it are two-dimensional: the flow becomes chaotic due to the proliferation of events where axisymmetric vortex pairs may be either created (vortex splitting) or annihilated (vortex merging). In this paper, we present direct numerical simulations, using the finitely extensible nonlinear elastic-Peterlin (FENE-P) constitutive equation to model the polymer dynamics, which reproduce the experimental observations with great accuracy and elucidate the reasons for the onset of this surprising dynamics. Starting from the Newtonian limit and increasing progressively the fluid's elasticity, we demonstrate that the VMS dynamics is not associated with the well-known Taylor vortices, but with a steady pattern of elastically induced axisymmetric vortex pairs known as diwhirls. The amount of angular momentum carried by these elastic vortices becomes increasingly small as the fluid's elasticity increases and it eventually reaches a marginal level. When this occurs, the diwhirls become dynamically disconnected from the rest of the system and move independently from each other in the axial direction. It is shown that vortex merging and splitting events, along with local transient chaotic dynamics, result from the interactions among diwhirls, and that this complex spatio-temporal dynamics persists even at elasticity levels twice as large as those investigated experimentally.

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Section: Problem Formulation Dimensionless Parameters and Numerical M...supporting

confidence: 82%

Vortex merging and splitting events in viscoelastic Taylor–Couette flow

Lopez

2022

J. Fluid Mech.

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“…Moreover, this time step is even one order of magnitude smaller than our previous DNS of EDT TC flows (Song et al. 2019, 2021 a , b ). The simultaneous increases of mesh size in the azimuthal and the axial directions makes the calculation tremendously time intensive for our present computational resource.…”

Section: Figurementioning

confidence: 78%

Direct numerical simulation of elastic turbulence in the Taylor–Couette flow: transition pathway and mechanistic insight

Song

Liu²,

Lu³

et al. 2022

J. Fluid Mech.

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Three-dimensional elastic turbulence in Taylor–Couette flows of dilute polymer solutions has been realized and thoroughly investigated via direct numerical simulations. A novel flow transition pathway from elastically dominated turbulence to solitary vortex pairs (or diwhirls) and eventually to elastic turbulence is observed by decreasing the fluid inertia ( $Re$ ) over seven orders of magnitude, i.e. from $Re=1000$ to $0.0001$ . The dominant spatio-temporal flow features in the elastic turbulence regime are those of large-scale unsteady diwhirls and small-scale axial and azimuthal travelling waves in the outer and inner halves of the gap, respectively. Moreover, it is conclusively shown that production of turbulent kinetic energy in purely elastic turbulence solely arises due to the stochastic nature of polymer stretch/relaxation. Overall, based on this comprehensive numerical investigation, the differences in the underlying fluid physics that give rise to turbulent fluctuations in elastically dominated and purely elastic turbulence have been delineated.

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“…All the three approaches above are covered in this review within the context of the Oldroyd-B model and its refinements. It is important to note that, in recent times, direct numerical simulations of viscoelastic flows complement the aforementioned approaches, providing detailed structural information in the nonlinear regime [54,55,56,57,58,59,60]. The computational expense, however, implies that the parameter space explored by such simulations is necessarily restricted, a limitation that is amplified by the high-dimensional nature of the parameter space characterizing viscoelastic shearing flows.…”

Section: Introductionmentioning

confidence: 99%