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The effect of side walls on the stability of falling films

DOI zum Zitieren der Version auf EPub Bayreuth:
URN to cite this document: urn:nbn:de:bvb:703-epub-7649-5

Title data

Mohamed, Hammam ; Sesterhenn, Jörn ; Biancofiore, Luca:
The effect of side walls on the stability of falling films.
In: Journal of Fluid Mechanics. Vol. 964 (2023) . - A40.
ISSN 0022-1120
DOI der Verlagsversion:

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We study the influence of side walls on the stability of falling liquid films. We combine a temporal biglobal stability analysis based on the linearised Navier–Stokes equations with experiments measuring the spatial growth rate of sinusoidal waves flowing downstream an inclined channel. Very good agreement was found when comparing the theoretical and experimental results. Strong lateral confinement of the channel stabilises the flow. In the wavenumber-Reynolds number space, the instability region experiences a fragmentation due to selective damping of moderate wavenumbers. For this range of parameters, the three-dimensional confined problem shows several prominent stability modes which are classified into two categories, the well-known Kapitza hydrodynamic instability mode (H-mode) and a new unstable mode, we refer to it as wall-mode (W-mode). The two mode types are stabilised differently, where the H-modes are stabilised at small wavenumbers, while the W-modes experience stabilisation at high wavenumbers, and at sufficiently small channel widths, only the W-mode is observed. The reason behind the unique H-modes stabilisation is that they become analogous to waveguide modes, which can not propagate below a certain cut-off wavenumber. The spatial structure of the eigenmodes experiences significant restructuring at wavenumbers smaller than the most damped wavenumber. The mode switching preserves the spatial symmetry of the unstable mode.

Further data

Item Type: Article in a journal
Keywords: thin films
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Institutions of the University: Faculties > Faculty of Engineering Science > Chair Technical Mechanics and Fluid Mechanics > Chair Technical Mechanics and Fluid Mechanics - Univ.-Prof. Dr. Jörn Lothar Sesterhenn
Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Technical Mechanics and Fluid Mechanics
Language: English
Originates at UBT: Yes
URN: urn:nbn:de:bvb:703-epub-7649-5
Date Deposited: 28 Mar 2024 05:48
Last Modified: 28 Mar 2024 05:49


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