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Stability of developing film flow down an inclined surface

Ramadurgam, Sarath and Chakravarthy, RVK and Tomar, Gaurav and Govindarajan, Rama (2012) Stability of developing film flow down an inclined surface. In: PHYSICS OF FLUIDS, 24 (10).

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Official URL: http://dx.doi.org/10.1063/1.4758299


Film flows on inclined surfaces are often assumed to be of constant thickness, which ensures that the velocity profile is half-Poiseuille. It is shown here that by shallow water theory, only flows in a portion of Reynolds number-Froude number (Re-Fr) plane can asymptotically attain constant film thickness. In another portion on the plane, the constant thickness solution appears as an unstable fixed point, while in other regions the film thickness seems to asymptote to a positive slope. Our simulations of the Navier-Stokes equations confirm the predictions of shallow water theory at higher Froude numbers, but disagree with them at lower Froude numbers. We show that different regimes of film flow show completely different stability behaviour from that predicted earlier. Supercritical decelerating flows are shown to be always unstable, whereas accelerating flows become unstable below a certain Reynolds number for a given Froude number. Subcritical flows on the other hand are shown to be unstable above a certain Reynolds number. In some range of parameters, two solutions for the base flowexist, and the attached profile is found to be more stable. All flows except those with separation become more stable as they proceed downstream. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.4758299]

Item Type: Journal Article
Additional Information: Copyright for this article belongs to American Institute of Physics, USA
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Depositing User: Francis Jayakanth
Date Deposited: 21 Dec 2012 03:46
Last Modified: 21 Dec 2012 03:46
URI: http://eprints.iisc.ac.in/id/eprint/45491

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