Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session D27: Flow Instability: Interfacial and Thin Film I
2:30 PM–4:40 PM,
Sunday, November 18, 2018
Georgia World Congress Center Room: B315
Chair: Ranganathan Narayanan, University of Florida
Abstract ID: BAPS.2018.DFD.D27.3
Abstract: D27.00003 : Stability analysis of evaporating falling liquid films
2:56 PM–3:09 PM
In order to improve the understanding of the wavy dynamics of evaporating falling liquid films, we have performed a linear stability analysis by solving the classical Orr-Sommerfeld eigenvalue problem. The key parameters of the analysis are: (i) Marangoni number $(Ma)$, describing the relation between the thermocapillary stress to the viscous stress, and (ii) the evaporation parameter $(E)$, representing the ratio between the viscous and evaporative time scales.
For small $Ma$, a new unstable mode (S-mode) is observed, resulting from the change of surface tension due to the temperature gradient along the free surface. More interestingly, for a specific Ma, the S-mode and H-mode (hydrodynamic mode, due to surface inclination) combine into one unstable region, thus reinforcing each other, leading to a possible formation of dry spots. When the liquid is volatile, a new instability is detected due to vapor recoil which destabilizes the flow in a similar fashion as thermocapillarity. Vapour recoil is also accompanied by a significant thinning of the film, accelerating the film's rupture.
Finally, direct numerical simulations are performed to verify the effects of $Ma$ and $E$ on the stability of the liquid films and the results are found to be in agreement with the theory.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.DFD.D27.3
The American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics.
1 Physics Ellipse, College Park, MD 20740-3844
Editorial Office 1 Research Road, Ridge, NY 11961-2701 (631) 591-4000
Office of Public Affairs 529 14th St NW, Suite 1050, Washington, D.C. 20045-2001 (202) 662-8700