Laminar-turbulent patterns with rough walls

Laminar-turbulent patterns with rough walls Oblique large-scale laminar-turbulent patterns are found near the onset of turbulence in subcritical planar shear flows. Their robustness to the introduction of wall roughness is investigated numerically in plane Couette flow as a function of the Reynolds number and the roughness height. The effect of roughness is considered on either one or two walls and is modeled numerically using a parametric model suggested recently [Busse and Sandham, J. Fluid Mech. 712, 169 (2012)JFLSA70022-112010.1017/jfm.2012.408]. In the case of two rough walls, the patterns are robust for a mean roughness height up to 10% of the wall gap, but the flow shows larger turbulent fractions with increasing roughness height. In the case of one rough wall only, the trend is similar, but the onset Reynolds number decreases faster with increasing roughness height. Roughness height levels above 15% of the wall gap give rise to new coherent structures, including turbulent bands with nonoblique interfaces. The energetic efficiency of the various regimes is investigated by monitoring the friction factor versus the friction Reynolds number. The mechanisms allowing for streamwise localization of the stripe patterns are discussed, with or without roughness, in the light of various low-order models. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review Fluids American Physical Society (APS)

Laminar-turbulent patterns with rough walls

Preview Only

Laminar-turbulent patterns with rough walls

Abstract

Oblique large-scale laminar-turbulent patterns are found near the onset of turbulence in subcritical planar shear flows. Their robustness to the introduction of wall roughness is investigated numerically in plane Couette flow as a function of the Reynolds number and the roughness height. The effect of roughness is considered on either one or two walls and is modeled numerically using a parametric model suggested recently [Busse and Sandham, J. Fluid Mech. 712, 169 (2012)JFLSA70022-112010.1017/jfm.2012.408]. In the case of two rough walls, the patterns are robust for a mean roughness height up to 10% of the wall gap, but the flow shows larger turbulent fractions with increasing roughness height. In the case of one rough wall only, the trend is similar, but the onset Reynolds number decreases faster with increasing roughness height. Roughness height levels above 15% of the wall gap give rise to new coherent structures, including turbulent bands with nonoblique interfaces. The energetic efficiency of the various regimes is investigated by monitoring the friction factor versus the friction Reynolds number. The mechanisms allowing for streamwise localization of the stripe patterns are discussed, with or without roughness, in the light of various low-order models.
Loading next page...
 
/lp/aps_physical/laminar-turbulent-patterns-with-rough-walls-b1N1L2Oika
Publisher
The American Physical Society
Copyright
Copyright © ©2017 American Physical Society
eISSN
2469-990X
D.O.I.
10.1103/PhysRevFluids.2.073901
Publisher site
See Article on Publisher Site

Abstract

Oblique large-scale laminar-turbulent patterns are found near the onset of turbulence in subcritical planar shear flows. Their robustness to the introduction of wall roughness is investigated numerically in plane Couette flow as a function of the Reynolds number and the roughness height. The effect of roughness is considered on either one or two walls and is modeled numerically using a parametric model suggested recently [Busse and Sandham, J. Fluid Mech. 712, 169 (2012)JFLSA70022-112010.1017/jfm.2012.408]. In the case of two rough walls, the patterns are robust for a mean roughness height up to 10% of the wall gap, but the flow shows larger turbulent fractions with increasing roughness height. In the case of one rough wall only, the trend is similar, but the onset Reynolds number decreases faster with increasing roughness height. Roughness height levels above 15% of the wall gap give rise to new coherent structures, including turbulent bands with nonoblique interfaces. The energetic efficiency of the various regimes is investigated by monitoring the friction factor versus the friction Reynolds number. The mechanisms allowing for streamwise localization of the stripe patterns are discussed, with or without roughness, in the light of various low-order models.

Journal

Physical Review FluidsAmerican Physical Society (APS)

Published: Jul 6, 2017

There are no references for this article.

Sorry, we don’t have permission to share this article on DeepDyve,
but here are related articles that you can start reading right now:

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial