A new way to describe the transition characteristics of a rotating-disk boundary-layer flow

Imayama, Shintaro; Alfredsson, P. Henrik; Lingwood, R. J.

doi:10.1063/1.3696020

Cited by 31 publications

(57 citation statements)

References 15 publications

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“…However, the amplitude of the wavepacket with the high-amplitude initial disturbance compares better with the result of Lingwood (1996), although it is not certain that the trailing edge of the wavepacket becomes fixed at R CA . However, Imayama et al (2012) suggested that the change in slope at around R = 545 in disturbance growth (their figure 5) could correspond to the so-called 'secondary front' suggested by Viaud, Serre & Chomaz (2011), leading to a cascade of absolutely unstable secondary instabilities and transition to turbulence. This evidence given by Imayama et al (2012) is perhaps the first experimental validation of secondary absolute instability of the primary nonlinear (steep-fronted) global mode shown in the DNS results of Viaud et al (2011).…”

Section: Studymentioning

confidence: 96%

An experimental study of edge effects on rotating-disk transition

2013

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The onset of transition for the rotating-disk flow was identified by Lingwood (J. Fluid. Mech., vol. 299, 1995, pp. 17-33) as being highly reproducible, which motivated her to look for absolute instability of the boundary-layer flow; the flow was found to be locally absolutely unstable above a Reynolds number of 507. Global instability, if associated with laminar-turbulent transition, implies that the onset of transition should be highly repeatable across different experimental facilities. While it has previously been shown that local absolute instability does not necessarily lead to linear global instability: Healey (J. Fluid. Mech., vol. 663, 2010, pp. 148-159) has shown, using the linearized complex Ginzburg-Landau equation, that if the finite nature of the flow domain is accounted for, then local absolute instability can give rise to linear global instability and lead directly to a nonlinear global mode. Healey (J. Fluid. Mech., vol. 663, 2010, pp. 148-159) also showed that there is a weak stabilizing effect as the steep front to the nonlinear global mode approaches the edge of the disk, and suggested that this might explain some reports of slightly higher transition Reynolds numbers, when located close to the edge. Here we look closely at the effects the edge of the disk have on laminar-turbulent transition of the rotatingdisk boundary-layer flow. We present data for three different edge configurations and various edge Reynolds numbers, which show no obvious variation in the transition Reynolds number due to proximity to the edge of the disk. These data, together with the application (as far as possible) of a consistent definition for the onset of transition to others' results, reduce the already relatively small scatter in reported transition Reynolds numbers, suggesting even greater reproducibility than previously thought for 'clean' disk experiments. The present results suggest that the finite nature of the disk, present in all real experiments, may indeed, as Healey (J. Fluid. Mech., vol. 663, 2010, pp. 148-159) suggests, lead to linear global instability as a first step in the onset of transition but we have not been able to verify a correlation between the transition Reynolds number and edge Reynolds number.

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Section: Studymentioning

confidence: 96%

An experimental study of edge effects on rotating-disk transition

2013

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“…To the best of the authors' knowledge no such experiments have yet taken place. Certainly in the Newtonian regime a wealth of literature exists, and this is currently a topic of particular interest, see Imayama et al [22][23][24], for example. Personal communication with these authors has revealed the difficulty of obtaining consistently accurate experimental results; therefore we can only envisage that the introduction of non-Newtonian fluids would serve to significantly complicate any experimental procedure.…”

Section: Discussionmentioning

confidence: 99%

Quantifying non-Newtonian effects in rotating boundary-layer flows

Griffiths

Garrett

Stephen

et al. 2017

European Journal of Mechanics - B/Fluids

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The stability of the boundary-layer on a rotating disk is considered for fluids that adhere to a non-Newtonian governing viscosity relationship. For fluids with shear-rate dependent viscosity the base flow is no longer an exact solution of the Navier-Stokes equations, however, in the limit of large Reynolds number the flow inside the three-dimensional boundary-layer can be determined via a similarity solution.The convective instabilities associated with flows of this nature are described both asymptotically and numerically via separate linear stability analyses. Akin to previous Newtonian studies it is found that there exists two primary modes of instability; the upper-branch type I modes, and the lower-branch type II modes. Results show that both these modes can be stabilised or destabilised depending on the choice of non-Newtonian viscosity model. A number of comments are made regarding the suitability of some of the more well-known non-Newtonian constitutive relationships within the context of the rotating disk model. Such a study is presented with a view to suggesting potential control mechanisms for flows that are practically relevant to the turbo-machinery industry.

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“…[1], see their figure 1. A hot-wire probe, with a single sensor made of platinum, is operated by a constant temperature anemometer (CTA) with an overheat ratio of 0.8.…”

Section: Introductionmentioning

confidence: 96%