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Global stability of the rotating-disc boundary layer with an axial magnetic field

Thomas, Christian and Davies, Christopher ORCID: https://orcid.org/0000-0002-5592-9541 2013. Global stability of the rotating-disc boundary layer with an axial magnetic field. Journal of Fluid Mechanics 724 , pp. 519-526. 10.1017/jfm.2013.162

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Abstract

A numerical study is conducted to investigate the influence of a uniform axial magnetic field on the global linear stability of the rotating-disc boundary layer. Simulation results obtained using a radially homogenized base flow were found to be in excellent agreement with an earlier linear stability analysis, which indicated that an axial magnetic field can locally suppress both convective and absolute instabilities. However, the numerical results obtained for the genuine, radially inhomogeneous, flow indicate that a global form of instability develops for sufficiently large magnetic fields. The qualitative nature of the global instability is similar to that which was observed in a previous study, where mass suction was applied at the rotating disc surface. It is shown that, just as for the case with mass suction, it is possible to explain the promotion of global instability by considering a model that includes detuning effects, which are associated with the radial variation of locally defined absolute temporal frequencies. The recurrence of the same type of instability behaviour when two distinct flow control strategies are implemented, one using suction and the other an axial magnetic field, indicates that the phenomena described by the model may be considered generic.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Mathematics
Subjects: Q Science > QA Mathematics
T Technology > TJ Mechanical engineering and machinery
Uncontrolled Keywords: absolute/convective instability; boundary layer stability; flow control
Additional Information: Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0022-1120/ (accessed 21/02/2014).
Publisher: Cambridge University Press
ISSN: 2152-5102
Date of First Compliant Deposit: 30 March 2016
Last Modified: 06 Jan 2024 04:52
URI: https://orca.cardiff.ac.uk/id/eprint/47502

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