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Numerical investigation of the evolution and breakup of an evaporating liquid film on a structured wall

Bender, Achim and Stephan, Peter and Gambaryan-Roisman, Tatiana :
Numerical investigation of the evolution and breakup of an evaporating liquid film on a structured wall.
[Online-Edition: https://doi.org/10.1016/j.ijheatfluidflow.2018.01.013]
In: International Journal of Heat and Fluid Flow, 70 104 - 113. ISSN 0142-727X
[Article] , (2018)

Official URL: https://doi.org/10.1016/j.ijheatfluidflow.2018.01.013

Abstract

Abstract This paper examines the evolution and rupture of a thin liquid film evaporating on a structured wall and the concomitant heat and mass transport. The heat is supplied either from the side of the wall or from the hot ambient gas. An evolution equation for the film thickness is derived in the framework of the long-wave theory under the assumption that the film thickness is small compared to the length scale of film deformation. The resulting fourth order partial differential equation is solved numerically employing a finite difference scheme using a {MATLAB} code. The results show that, in the case of a hot wall, the film breakup may occur even in the absence of evaporation. The reason for this breakup is Marangoni convection driven by uneven temperature distribution at the liquid-gas interface due to the wall structure. With increasing evaporation rate the rupture time decreases and the position at which the rupture occurs is shifted towards the crests of the wall topography. Additionally, it is found that the wave length of the wall structure has a non-monotonous effect on rupture time. If the film is heated by the ambient gas, the liquid-gas interface tends to follow the wall topography shape.

Item Type: Article
Erschienen: 2018
Creators: Bender, Achim and Stephan, Peter and Gambaryan-Roisman, Tatiana
Title: Numerical investigation of the evolution and breakup of an evaporating liquid film on a structured wall
Language: English
Abstract:

Abstract This paper examines the evolution and rupture of a thin liquid film evaporating on a structured wall and the concomitant heat and mass transport. The heat is supplied either from the side of the wall or from the hot ambient gas. An evolution equation for the film thickness is derived in the framework of the long-wave theory under the assumption that the film thickness is small compared to the length scale of film deformation. The resulting fourth order partial differential equation is solved numerically employing a finite difference scheme using a {MATLAB} code. The results show that, in the case of a hot wall, the film breakup may occur even in the absence of evaporation. The reason for this breakup is Marangoni convection driven by uneven temperature distribution at the liquid-gas interface due to the wall structure. With increasing evaporation rate the rupture time decreases and the position at which the rupture occurs is shifted towards the crests of the wall topography. Additionally, it is found that the wave length of the wall structure has a non-monotonous effect on rupture time. If the film is heated by the ambient gas, the liquid-gas interface tends to follow the wall topography shape.

Journal or Publication Title: International Journal of Heat and Fluid Flow
Volume: 70
Uncontrolled Keywords: Long-wave theory
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institute for Technical Thermodynamics (TTD)
Profile Areas
Profile Areas > Thermo-Fluids & Interfaces
Date Deposited: 14 Feb 2018 12:12
DOI: 10.1016/j.ijheatfluidflow.2018.01.013
Official URL: https://doi.org/10.1016/j.ijheatfluidflow.2018.01.013
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