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Stability of the channel flow - new phenomena in an old problem

Title data

Kögel, Armin ; Aksel, Nuri:
Stability of the channel flow - new phenomena in an old problem.
In: Acta Mechanica. Vol. 231 (March 2020) Issue 3 . - pp. 1063-1082.
ISSN 1619-6937
DOI: https://doi.org/10.1007/s00707-019-02568-8

Official URL: Volltext

Abstract in another language

In this article, we show an unexpected effect of side walls on the stability of gravity-driven viscous film flows over flat substrates in an open channel. Until now, it was assumed that side walls have a stabilizing effect on the flow, but the qualitative structure of the neutral curve remains the same. We show a fragmentation of the stability chart that was only known from undulated substrates. The cause of the fragmentation is a distinct damping of waves with a certain frequency that is independent of the underlying instability of the two-dimensional flow. This paper provides a detailed parameter study that identifies the channel width as the decisive parameter for the damping frequency. In addition, the damping is not an effect of flat side walls exclusively, since corrugated side walls have qualitatively the same impact on the stability chart. Furthermore, we demonstrate that the curvature of the emerging wave’s crest line has a non-monotonous dependency on the frequency and shows a distinct maximum. The frequency of this maximum shows the same behavior as the damping frequency when the channel width is varied. We therefore assume a relation between the wave’s curvature and its growth rate, both massively affected by the side walls.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science > Former Professors
Faculties > Faculty of Engineering Science > Chair Technical Mechanics and Fluid Mechanics
Faculties > Faculty of Engineering Science > Former Professors > Chair Technical Mechanics and Fluid Mechanics - Univ.-Prof. Dr. Nuri Aksel
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 16 Jun 2020 08:23
Last Modified: 16 Jun 2020 09:24
URI: https://eref.uni-bayreuth.de/id/eprint/55501