Laminar-turbulent boundary-layer transition over a rough rotating disk

Zoueshtiagh, Farzam; Ali, Reza; Colley, Andrew J.; Thomas, Peter J.; Carpenter, Peter W.

doi:10.1063/1.1586916

Cited by 20 publications

(15 citation statements)

References 12 publications

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“…Their results appear to display some qualitative similarities with the data reported here in Figures 1 and 2. However, we believe that a comparison between the data of Zoueshtiagh et al 21 and the results presented here is not justified for several reasons. The two main reasons being that, first, the roughness considered in the present study is very different compared to the random quartz-grain roughness in Zoueshtiagh et al 21 Second, the facility of Zoueshtiagh et al 21 incorporated a lid covering the disk (see their Fig.…”

Section: Discussionmentioning

confidence: 68%

“…Zoueshtiagh et al 21 documented a short set of experimental data for velocity profiles over quartz-grain roughened disks. Their results appear to display some qualitative similarities with the data reported here in Figures 1 and 2.…”

Section: Discussionmentioning

confidence: 99%

“…However, the existing studies focussed almost exclusively on the effects of a small number of roughness elements arranged to form certain roughness patterns, the goal being to excite particular disturbance modes to test their characteristics for the development of specific control mechanisms. 9,10,[18][19][20] Work with more general roughness was briefly considered by Zoueshtiagh et al 21 for a rotating disk and, in more depth, by Watanabe et al 22 Zoueshtiagh et al 21 documented a short set of experimental data for velocity profiles over quartz-grain roughened disks and these will be revisited here after the presentation of the current results. Watanabe et al 22 studied uniformly distributed roughness on a rotating cone.…”

Section: Introductionmentioning

confidence: 99%

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The effect of anisotropic and isotropic roughness on the convective stability of the rotating disk boundary layer

et al. 2015

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A theoretical study investigating the effects of both anisotropic and isotropic surface roughness on the convective stability of the boundary-layer flow over a rotating disk is described. Surface roughness is modelled using a partial-slip approach, which yields steady-flow profiles for the relevant velocity components of the boundary-layer flow which are a departure from the classic von Kármán solution for a smooth disk. These are then subjected to a linear stability analysis to reveal how roughness affects the stability characteristics of the inviscid Type I (or cross-flow) instability and the viscous Type II instability that arise in the rotating disk boundary layer. Stationary modes are studied and both anisotropic (concentric grooves and radial grooves) and isotropic (general) roughness are shown to have a stabilizing effect on the Type I instability. For the viscous Type II instability, it was found that a disk with concentric grooves has a strongly destabilizing effect, whereas a disk with radial grooves or general isotropic roughness has a stabilizing effect on this mode. In order to extract possible underlying physical mechanisms behind the effects of roughness, and in order to reconfirm the results of the linear stability analysis, an integral energy equation for three-dimensional disturbances to the undisturbed three-dimensional boundary-layer flow is used. For anisotropic roughness, the stabilizing effect on the Type I mode is brought about by reductions in energy production in the boundary layer, whilst the destabilizing effect of concentric grooves on the Type II mode results from a reduction in energy dissipation. For isotropic roughness, both modes are stabilized by combinations of reduced energy production and increased dissipation.

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Section: Discussionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of anisotropic and isotropic roughness on the convective stability of the rotating disk boundary layer

et al. 2015

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“…Zoueshtiagh et al [47] investigated the flow over rough rotating disks. They carried out observations to determine the critical Reynolds number for the laminar-turbulent transition of the boundary layer over rough rotating disks.…”

Section: Reason For the Reduced Critical Reynolds Numbers For Loose-bmentioning

confidence: 99%

Rotating-disk-type flow over loose boundaries

Thomas¹,

Zoueshtiagh²

2006

J Eng Math

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Rotating-disk-type flow of a liquid over a loose boundary, such as a layer of sand, is investigated. For this flow the formation of a new large-scale spiral pattern has been discovered. The new pattern is reminiscent of the Type-I spiral-vortex structures which characterize the laminar-turbulent transition region of boundary layers over rigid rotating disks. Flow visualizations reveal that the new pattern and the Type-I spiral vortices co-exist in the loose-boundary flow. The research investigating the origin of the new largescale pattern is reviewed. Then photographs from flow visualizations are analysed to obtain estimates for the critical Reynolds number for which Type-I spiral vortices first appear for the loose-boundary flow and for the critical Reynolds numbers for the laminar-turbulent transition of the boundary layer. The results suggest that Type-I vortices appear at much lower Reynolds numbers over loose boundaries in comparison with flow over rigid rotating disks and that transition also appears to be advanced to much lower Reynolds numbers. The discussion of the results suggests that advanced transition arises from disturbances introduced into the flow after the loose boundary has been mobilized and not from disturbances associated with the roughness that the surfaces of the granular layer represents to the flow while grains are at rest.

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“…Figure 3(a) compares the measured mean radial velocity on the 154 mm rotating disk in quiescent fluid with the above. The results reveal the effects of roughness (due to spray painting the disk 10 ) and of using a finite disk. The near-surface radial jet reaches a substantially higher peak value than that for the smooth infinite disk.…”

mentioning

confidence: 92%

Instability of the radial flow over a rotating disk in a separated edgewise stream

Raghav

Komerath

2013

Physics of Fluids

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We present velocity field measurements showing the instability of the radial flow over a rotating disk in a separated flow due to an edgewise freestream. A uniform edgewise stream significantly modifies the radial jet profile. Under separated flow conditions, co-rotating vortical structures form at the edge of the radial jet layer. The results establish that the discrete structures formed in the breakup of the radial flow layer on a rotor blade in retreating blade stall are also seen in the case of flow over a rotating disk.

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Laminar-turbulent boundary-layer transition over a rough rotating disk

Cited by 20 publications

References 12 publications

The effect of anisotropic and isotropic roughness on the convective stability of the rotating disk boundary layer

The effect of anisotropic and isotropic roughness on the convective stability of the rotating disk boundary layer

Rotating-disk-type flow over loose boundaries

Instability of the radial flow over a rotating disk in a separated edgewise stream

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