Logo LMFA
And on the seventh day, He exited from append mode.

Transition near the edge of a rotating disk

Benoît PIER

Laboratoire de mécanique des fluides et d'acoustique, École centrale de Lyon – CNRS – Université Claude-Bernard Lyon 1 – INSA, 36 avenue Guy-de-Collongue, 69134 Écully cedex, France

Journal of Fluid Mechanics 737, R1 (9 pages) (2013)

Abstract:

The rotating-disk boundary layer is generally considered as an example of a flow that displays a robust transition from laminar to turbulent régimes. By taking into account disks of finite radius, Healey (2010) has predicted a stabilizing effect of the boundary condition, but Imayama et al. (2013) were unable to confirm this prediction experimentally. Following these contradictory results, the present experimental investigation revisits the rotating-disk boundary layer, without any artificially imposed excitation, and studies in further detail the dynamics prevailing in the region closely surrounding the edge of the disk, as well as the flow beyond the disk. Azimuthal mean velocities and fluctuation amplitudes are recorded with small steps in radial and axial directions for a wide range of disk sizes. An objective criterion is used to define the onset of fluctuations consistently over a large data set. Two distinct mechanisms for the onset of fluctuations are identified. In particular, it is found that the flow over the edge of the disk acts as a strong source of fluctuations. Explanations and suggestions for a possible reconciliation of previous studies are given.

doi:10.1017/jfm.2013.578

hal-00907846

2013d_pier_jfm.pdf

Copyleft © all rights reversed  —  http://www.lmfa.fr/perso/Benoit.Pier/pub/2013d.php viewed by 44.212.26.248 - 28/03/2024 - 09:40:55