Turbulent-laminar coexistence in wall flows with Coriolis, buoyancy or Lorentz forces
2012 (English)In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 704, 137-172 p.Article in journal (Refereed) Published
Direct numerical simulations of subcritical rotating, stratified and magnetohydrodynamic wall-bounded flows are performed in large computational domains, focusing on parameters where laminar and turbulent flow can stably coexist. In most cases, a regime of large-scale oblique laminar-turbulent patterns is identified at the onset of transition, as in the case of pure shear flows. The current study indicates that this oblique regime can be shifted up to large values of the Reynolds number R e by increasing the damping by the Coriolis, buoyancy or Lorentz force. We show evidence for this phenomenon in three distinct flow cases: plane Couette flow with spanwise cyclonic rotation, plane magnetohydrodynamic channel flow with a spanwise or wall-normal magnetic field, and open channel flow under stable stratification. Near-wall turbulence structures inside the turbulent patterns are invariably found to scale in terms of viscous wall units as in the fully turbulent case, while the patterns themselves remain large-scale with a trend towards shorter wavelength for increasing Re. Two distinct regimes are identified: at low Reynolds numbers the patterns extend from one wall to the other, while at large Reynolds number they are confined to the near-wall regions and the patterns on both channel sides are uncorrelated, the core of the flow being highly turbulent without any dominant large-scale structure.
Place, publisher, year, edition, pages
2012. Vol. 704, 137-172 p.
transition to turbulence, turbulent flows
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-100777DOI: 10.1017/jfm.2012.224ISI: 000306528700007ScopusID: 2-s2.0-84865529737OAI: oai:DiVA.org:kth-100777DiVA: diva2:545017
FunderSwedish Research Council, 621-2010-4147Swedish e‐Science Research Center
QC 201208172012-08-172012-08-172013-04-08Bibliographically approved