Localized turbulence structures in transitional rectangular-duct flow

Takeishi, Kenichiro; Kawahara, Genta; Wakabayashi, Hiroki; Uhlmann, Markus; Pinelli, Alfredo

doi:10.1017/jfm.2015.546

Cited by 19 publications

(16 citation statements)

References 25 publications

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“…Figure 17 Turbulent-laminar patterns in annular pipe flow (a,b,c) adapted from Ishida et al (2016), and in duct flow (d,e,f) adapted from Takeishi et al (2015). The aspect ratio A is defined as A = (rout + r in )/(rout − r in ) for annular pipe flow and as A = Lspan/height for duct flow.…”

Section: Model Waleffe Flow: Directed Percolationmentioning

confidence: 99%

Patterns in Wall-Bounded Shear Flows

Tuckerman

Chantry

Barkley

2020

Annu. Rev. Fluid Mech.

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Experiments and numerical simulations have shown that turbulence in transitional wall-bounded shear flows frequently takes the form of long oblique bands if the domains are sufficiently large to accommodate them. These turbulent bands have been observed in plane Couette flow, plane Poiseuille flow, counter-rotating Taylor–Couette flow, torsional Couette flow, and annular pipe flow. At their upper Reynolds number threshold, laminar regions carve out gaps in otherwise uniform turbulence, ultimately forming regular turbulent–laminar patterns with a large spatial wavelength. At the lower threshold, isolated turbulent bands sparsely populate otherwise laminar domains, and complete laminarization takes place via their disappearance. We review results for plane Couette flow, plane Poiseuille flow, and free-slip Waleffe flow, focusing on thresholds, wavelengths, and mean flows, with many of the results coming from numerical simulations in tilted rectangular domains that form the minimal flow unit for the turbulent–laminar bands.

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Section: Model Waleffe Flow: Directed Percolationmentioning

confidence: 99%

Patterns in Wall-Bounded Shear Flows

Tuckerman

Chantry

Barkley

2020

Annu. Rev. Fluid Mech.

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“…In particular, each patch of turbulent fluctuations extends over the full cross-section, i.e., they are rather homogeneous in the z direction with straight laminar-turbulent interfaces. (19,23), and (c) (19,26).…”

Section: Temporal Dynamics Of Localised Turbulent Structuresmentioning

confidence: 99%

Turbulent bifurcations in intermittent shear flows: From puffs to oblique stripes

2017

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Localised turbulent structures such as puffs or oblique stripes are building blocks of the intermittency regimes in subcritical wall-bounded shear flows. These turbulent structures are investigated in incompressible pressure-driven annular pipe flow using direct numerical simulations in long domains. For low enough radius ratio η, these coherent structures have a dynamics comparable to that of puffs in cylindrical pipe flow. For η larger than 0.5, they take the shape of helical stripes inclined with respect to the axial direction. The transition from puffs to stripes is analysed statistically by focusing on the axisymmetry properties of the associated large-scale flows. It is shown that the transition is gradual : as the azimuthal confinement relaxes, allowing for an azimuthal large-scale component, oblique stripes emerge as predicted in the planar limit. The generality of this transition mechanism is discussed in the context of subcritical shear flows.2

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“…In flows with one unconstrained direction, large-scale turbulent-laminar intermittency can manifest itself only in that direction. Pipe flow is the classic example of such a system [2], but other examples are variants such as duct flow [3] and annular pipe flow [4], and also constrained Couette flow between circular cylinders where the height and gap are both much smaller than the circumference [5]. In terms of large-scale phenomena, these systems are viewed as one dimensional.…”

Section: Introductionmentioning

confidence: 99%

Statistical transition to turbulence in plane channel flow

2020

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Intermittent turbulent-laminar patterns characterize the transition to turbulence in pipe, plane Couette, and plane channel flows. The time evolution of turbulent-laminar bands in plane channel flow is studied via direct numerical simulations using the parallel pseudospectral code CHANNELFLOW in a narrow computational domain tilted by 24 • with respect to the streamwise direction. Mutual interactions between bands are studied through their propagation velocities. Energy profiles show that the flow surrounding isolated turbulent bands returns to the laminar base flow over large distances. Depending on the Reynolds number, a turbulent band can either decay to laminar flow or split into two bands. As with past studies of other wall-bounded shear flows, in most cases survival probabilities are found to be consistent with exponential distributions for both decay and splitting, indicating that the processes are memoryless. Statistically estimated mean lifetimes for decay and splitting are plotted as a function of the Reynolds number and lead to the estimation of a critical Reynolds number Re cross 965, where decay and splitting lifetimes cross at greater than 10 6 advective time units. The processes of splitting and decay are also examined through analysis of their Fourier spectra. The dynamics of large-scale spectral components seem to statistically follow the same pathway during the splitting of a turbulent band and may be considered as precursors of splitting.

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Localized turbulence structures in transitional rectangular-duct flow

Cited by 19 publications

References 25 publications

Patterns in Wall-Bounded Shear Flows

Patterns in Wall-Bounded Shear Flows

Turbulent bifurcations in intermittent shear flows: From puffs to oblique stripes

Statistical transition to turbulence in plane channel flow

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