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

F. Zoueshtiagh, R. Ali, A. J. Colley, P. J. Thomas, P. W. Carpenter

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19 Citations (Scopus)
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Boundary-layer transition over a disk spinning under water is investigated. Transitional Reynolds numbers, Rec, and associated boundary-layer velocity profiles are determined from flow-visualizations and hot-film measurements, respectively. The value of Rec and the velocity profiles are studied as a function of the disk's surface roughness. It is found that transition over rough disks occurs in a similar fashion to that over smooth disks, i.e., abruptly and axisymmetrically at well-defined radii. Wall roughness has little effect on Rec until a threshold relative roughness is reached. Above the threshold Rec decreases sharply. The decrease is consistent with the drop one expects for our flow for the absolute instability discovered by Lingwood [J. Fluid Mech. 299, 17 (1995); 314, 373 (1996); 331, 405 (1997)]. This indicates that the Lingwood absolute instability may continue to play a major role in the transition process even for large relative roughness.

Original languageEnglish
Pages (from-to)2441-2444
Number of pages4
JournalPhysics of Fluids
Issue number8
Publication statusPublished - Aug 2003

ASJC Scopus subject areas

  • Condensed Matter Physics


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