A statistical study of spots in torsional Couette flow

Gal, Patrice Le; Tasaka, Yuji; Nagao, Jotaro; Cros, Anne; Yamaguchi, Kazuya

doi:10.1007/s10665-006-9100-z

Cited by 10 publications

(11 citation statements)

References 15 publications

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“…This critical Reynolds number is of the same order as that for the onset of surface switching. In the transition to turbulence, a turbulent spot or turbulence on the spiral vortices first appears at the edge of the disk, and subsequently spreading to become global turbulence, as has been observed in the flow between rotating and stationary disks (Cross & Le Gal 2002;Le Gal et al 2007). In the set-up used in the paper here, the surface shape changes greatly during the switching process, and such a change would shift the critical Reynolds number.…”

Section: Introductionmentioning

confidence: 80%

Flow transitions in the surface switching of rotating fluid

Tasaka

Iima

2009

J. Fluid Mech.

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We study 'surface switching' quantitatively in flows driven by the constant rotation of the endwall of an open cylindrical vessel reported by Suzuki, Iima & Hayase (Phys. Fluids, vol. 18, 2006, p. 101701): the deformed free surface switches between axisymmetric and non-axisymmetric shapes accompanied by irregular vertical oscillation. Detailed simultaneous measurements showed that the magnitude of the velocity fluctuations (turbulent intensity) temporally varies greatly and are strongly correlated with the surface height, suggesting that dynamic switching between laminar and turbulent states is accompanied by vessel-scale surface shape changes. The study also identified clear hysteresis in the turbulent intensity arising from changes in the Reynolds number; the bifurcation diagram consists of two overlapping branches representing a high-intensity (turbulent) state and a low-intensity (laminar) state. Based on the results, a switching mechanism is suggested.

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Section: Introductionmentioning

confidence: 80%

Flow transitions in the surface switching of rotating fluid

Tasaka

Iima

2009

J. Fluid Mech.

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“…Nature of the studies α Plane Couette flow [29] Theory/numerical simulations −21/4 ≤ α ≤ −1 Uniform-Shear flows [30] Theory −1 and −1/3 Plane Couette flow [31] Theory −1 Shear flows [32] Theory: simple balance between nonlinear advection and viscous terms −1 Plane Couette flow [33] Experimental −0.4 Channel flow [34] Experimental using a cross-jet as disturbance −3/2 Channel flow [35] Experimental −1 Pipe flow [36] Experimental using a cross-jet as disturbance −1.1 and −1.5 Torsional Couette flow [37] Experimental without external disturbance −1.5 Plane Poiseuille flow [38] Experimental using a jet as disturbance −1 E = W i/Re and it characterizes the polymer solution in a flow configuration with a characteristic length d.…”

Section: Flowmentioning

confidence: 99%

Transition to turbulence via flame patterns in viscoelastic Taylor–Couette flow

Latrache

Mutabazi

2021

Eur. Phys. J. E

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Transition to inertio-elastic turbulence in Taylor-Couette flow with shear-thinning and viscoelastic polymer solutions is investigated when the rotation rate of the inner cylinder is increased and the outer cylinder is fixed. In two polymer solutions of PEO with elastic number E ∈ {0.16; 0.30}, the first instability of the circular Couette flow appears as spirals propagating in opposite directions along the axis of cylinders. Just above the onset of the spirals pattern, the localized solitons of the strong radial inflow called flamelike flow appear abruptly inside waves. The abrupt apparition of the flame-like flow is the signature of the subcritical transition to turbulence. The number of the flame-like flows follows a Gaussian distribution at given Ta number. The averaged number of the flame-like flow increases as the rotation rate is increased and it saturates in the inertio-elastic turbulence. The soliton of the strong radial inflow (flame-pattern) is created when it amplitude exceeds a critical value. The distribution of the critical amplitudes of the flame patterns follows a Gaussian law at given Ta number. The transition to turbulence is described by a mathematical model based on an error function of the probability to observe a strong inflow (flame-pattern). The statistical data of the critical amplitude and the probability to observe the flame patterns are used with the mathematical model in order to determine the stability curve of the transition to turbulence. The analysis of the transition to turbulence is completed by the characterization of the spatiotemporal properties.

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“…Based on the successful generation of local turbulence in flows between stationary and rotating disks [24], we used three different disks that gave three gap sizes between the inner lateral wall of the vessel and the rim of the disk, ∆R,. The three disks used here are (A) ∆R = 0.10 mm (made of acrylic resin), (B) ∆R = 0.30 mm (glass, also used in [19]), and (C) ∆R = 1.05 mm (acrylic resin).…”

Section: A Experimental Setup and Proceduresmentioning

confidence: 99%

“…There is evidence that a small change in the disk-rim gap changes some of the characteristics in the rotating flow. For closed flows with a rotating disk in a cylindrical vessel, a model system for subcritical-flow instability problems in Couette flows, Le Gal et al [24] investigated the effect of the disk-rim gap and established that the appearance of local turbulence at the disk rim was clearly dependent on the size of the disk-rim gap, suggesting the possibility of controlling the internal noise by modifying the disk-rim gap.…”

Section: Direct Noise Injectionmentioning

confidence: 99%

Surface switching statistics of rotating fluid: Disk-rim gap effects

Tasaka

Iima

2017

Phys. Rev. E

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We examined the influence of internal noise on the irregular switching of the shape of the free surface of fluids in an open cylindrical vessel driven by a bottom disk rotating at constant speed [Suzuki, Iima, and Hayase, Phys. Fluids 18, 101701 (2006)PHFLE61070-663110.1063/1.2359740]. A slight increase in the disk-rim gap (less than 3% of the disk radius) was established experimentally to cause significant changes in this system, specifically, frequent appearance of the surface descending event connecting a nonaxisymmetric shape in strong mixing flow (turbulent flow) and an axisymmetric shape in laminar flow, as well as a shift in critical Reynolds number that define the characteristic states. The physical mechanism underlying the change is analyzed in terms of flow characteristics in the disk-rim gap, which acts as a noise source, and a mathematical model established from measurements of the surface height fluctuations with noise term.

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A statistical study of spots in torsional Couette flow

Cited by 10 publications

References 15 publications

Flow transitions in the surface switching of rotating fluid

Flow transitions in the surface switching of rotating fluid

Transition to turbulence via flame patterns in viscoelastic Taylor–Couette flow

Surface switching statistics of rotating fluid: Disk-rim gap effects

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