Transitional structures in annular Poiseuille flow depending on radius ratio

Ishida, Takahiro; Duguet, Yohann; Tsukahara, Takahiro

doi:10.1017/jfm.2016.192

Cited by 38 publications

(42 citation statements)

References 28 publications

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“…The laminar streamwise intervals have lengths of about 50h, consistently with those in pCf (Prigent et al 2002;Duguet et al 2010a;Brethouwer et al 2012). Such helical turbulence also occurs in aPf (Ishida et al 2016) with a similar value of the pitch angle. By reducing Re, the helical turbulence sustains until Re = 337.5 (Re τ = 24.0) and eventually decays at 325.…”

Section: Morphology Of Coherent Structuressupporting

confidence: 64%

Laminar–turbulent coexistence in annular Couette flow

et al. 2019

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Annular Couette flow is the flow between two coaxial cylinders driven by the axial translation of the inner cylinder. It is investigated using direct numerical simulation in long domains, with an emphasis on the laminar-turbulent coexistence regime found for marginally low values of the Reynolds number. Three distinct flow regimes are demonstrated as the radius ratio η is decreased from 0.8 to 0.5 and finally to 0.1. The high-η regime features helically-shaped turbulent patches coexisting with laminar flow, as in planar shear flows. The moderate-η regime does not feature any marked laminarturbulent coexistence. In an effort to discard confinement effects, proper patterning is however recovered by artificially extending the azimuthal span beyond 2π. Eventually, the low-η regime features localised turbulent structures different from the puffs commonly encountered in transitional pipe flow. In this new coexistence regime, turbulent fluctuations are surprisingly short-ranged. Implications are discussed in terms of phase transition and critical scaling.

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Section: Morphology Of Coherent Structuressupporting

confidence: 64%

Laminar–turbulent coexistence in annular Couette flow

et al. 2019

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“…As mentioned earlier, for annular Poiseuille flow in the limit of radius ratio tending to one, the pattern is, not unexpectedly, in the form of intertwined helices [26][27][28]. In the planar case, the effects of spanwise-rotation on thresholds and pattern wavelengths have also been studied [88], but their variations turn out to be more complicated than for PCF due to a different shear wall-normal dependence.…”

Section: Other Planar Configurationsmentioning

confidence: 88%

“…On the other hand in the small gap limit, when this ratio tends to one and the curvature of the fluid layer tends to zero, a laminar-turbulent organization takes place in the form of turbulent helices translating in the gap, locally anticipating the oblique bands of the planar case. The crossover between the two regimes has been studied as a function of the radius ratio [26][27][28]. In the same way, fluid motion induced by steadily counter-sliding the cylinders along their axis, yields annular Couette flow (more easily implemented numerically [29] than approximated experimentally) that connects to PCF in the small gap limit in the same way as annular to plane Poiseuille flow.…”

Section: Contextmentioning

confidence: 99%

Laminar-Turbulent Patterning in Transitional Flows

Manneville

2017

Entropy

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Wall-bounded flows experience a transition to turbulence characterized by the coexistence of laminar and turbulent domains in some range of Reynolds number R, the natural control parameter. This transitional regime takes place between an upper threshold R t above which turbulence is uniform (featureless) and a lower threshold R g below which any form of turbulence decays, possibly at the end of overlong chaotic transients. The most emblematic cases of flow along flat plates transiting to/from turbulence according to this scenario are reviewed. The coexistence is generally in the form of bands, alternatively laminar and turbulent, and oriented obliquely with respect to the general flow direction. The final decay of the bands at R g points to the relevance of directed percolation and criticality in the sense of statistical-physics phase transitions. The nature of the transition at R t where bands form is still somewhat mysterious and does not easily fit the scheme holding for pattern-forming instabilities at increasing control parameter on a laminar background. In contrast, the bands arise at R t out of a uniform turbulent background at a decreasing control parameter. Ingredients of a possible theory of laminar-turbulent patterning are discussed.Keywords: transition to/from turbulence; wall-bounded shear flow; plane Couette flow; turbulent patterning; phase transitions; directed percolationThe present Special-Issue contribution deals with the transition to turbulence in wall-bounded flows, an important case of systems driven far from equilibrium where patterns develop against a turbulent background. This active field of research is rapidly evolving, and important results have been obtained recently. To set the frame, in Section 1, I will summarize a recent paper reviewing the subject from a more general standpoint [1], enabling me to focus on a specific feature of this transition: the existence of a statistically well-organized laminar-turbulent patterning of flows along planar walls in some intermediate range of Reynolds numbers [R g , R t ]. The Reynolds number is the main control parameter of the problem. Its generic expression reads R = V /ν, in which V and are typical velocity and length scales, and ν the fluid's kinematic viscosity. R compares the typical shear rate V/ to the viscous diffusion rate over the same length scale ν/ 2 . R g is a global stability threshold marking unconditional return to laminar flow and R t some upper threshold beyond which turbulence is essentially uniform. After having taken the cylindrical shear configuration as an illustrating case in Section 2, I will turn to strictly planar cases in Section 3. The best understood part of the transition scenario, pattern decay at R g is considered in Section 4. How patterns emerge as R is decreased from large values is next examined in Section 5 before a discussion of perspectives and questions that, in my view, remain open in Section 6. I have tried to limit the bibliography to contributions of specific significance, historical or...

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“…Hysteresis is also present between Re l and Re g . In terms of the transitional structure, our previous study 10 revealed smooth alternations, with dependence on h, of the localized turbulent patterns: helical turbulence, helical puff, and straight puff. Robust helical turbulence corresponding to the turbulent stripe in pPf has been identified for high h !…”

Section: Introductionmentioning

confidence: 86%

“…Ishida et al 10 focused only on transitional structures, and statistical properties in aPf were not examined. Hence, this article would describe statistical results including the friction factor.…”

Section: Introductionmentioning

confidence: 99%

Friction factor of annular Poiseuille flow in a transitional regime

Ishida

Tsukahara

2017

Advances in Mechanical Engineering

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Annular Poiseuille flows in a transitional regime were investigated by direct numerical simulations with an emphasis on turbulent statistics including the friction factor that are affected by the presence of large-scale transitional structures. Five different radius ratios in the range of 0.1-0.8 and several friction Reynolds numbers in the range of 48-150 were analyzed to consider various flow states accompanied by characteristic transitional structures. Three characteristic structures, namely, turbulent-laminar coexistence referred to as ''(straight) puff,''''helical puff,'' and ''helical turbulence'' were observed. The selection of the structures depends on both the radius ratio and the Reynolds number. The findings indicated that despite the transitional state with a turbulent-laminar coexistence, the helical turbulence resulted in a friction factor that was as high as the fully turbulent value. In contrast, with respect to the occurrence of streamwise-finite transitional structures, such as straight/helical puffs, the friction factor decreased in a stepwise manner toward a laminar level. The turbulent statistics revealed asymmetric distributions with respect to the wall-normal direction wherein the profiles and magnitudes were significantly influenced by the occurrence of transitional structures.

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Transitional structures in annular Poiseuille flow depending on radius ratio

Cited by 38 publications

References 28 publications

Laminar–turbulent coexistence in annular Couette flow

Laminar–turbulent coexistence in annular Couette flow

Laminar-Turbulent Patterning in Transitional Flows

Friction factor of annular Poiseuille flow in a transitional regime

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