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Numerical investigation of evaporation in the developing region of laminar falling film flow under constant wall heat flux conditions
Published in
2010
Volume: 58
   
Issue: 1
Pages: 41 - 64
Abstract
A finite-volume-based incompressible flow algorithm on Cartesian grid is presented for the simulation of evaporation phenomena in a falling liquid film under low wall superheat conditions. The model employs the PLIC-VOF method to capture the free surface evolution, and the continuum surface force (CSF) approximation to emulate the effects of interfacial tension. The phase change process is represented through a source term in the interfacial cells, which is evaluated from the normal temperature gradients on either side of the interface. In order to evaluate these discontinuous temperature gradients across the interface accurately, a simple and efficient ghost fluid method has been implemented, which properly takes into account the dynamic evolution of the interface. The overall numerical model, including the phase change algorithm, has been validated against standard benchmark analytical results. Finally, the model is used to simulate the evaporating flow of a 2-D laminar, developing film falling over an inclined plane surface, subjected to constant wall heat flux. The results thus obtained, clearly illustrate the significance of inertial effects in the developing region of the falling film, which are generally neglected in the available analytical models. It is also observed, that the evaporation of fluid commences only after the growing thermal boundary layer reaches the interface, and the length of the nonevaporating section reduces with the increase in wall heat flux value. Copyright © Taylor & Francis Group, LLC.
About the journal
JournalNumerical Heat Transfer; Part A: Applications
ISSN10407782
Open AccessNo
Concepts (36)
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    Analytical model
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    Analytical results
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    Cartesian grid
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    Constant wall heat flux
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    CONTINUUM SURFACE FORCES
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    Developing regions
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    Dynamic evolution
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    FALLING FILM
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    FALLING FILM FLOW
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    FALLING LIQUID FILMS
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    FINITE-VOLUME
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    Free surfaces
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    Ghost fluid method
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    Inclined planes
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    Inertial effect
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    Interfacial tensions
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    Numerical investigations
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    Numerical models
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    Phase change
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    Phase change process
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    Source terms
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    SUPERHEAT CONDITIONS
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    Temperature gradient
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    Thermal boundary layer
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    VOF METHOD
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    Wall heat flux
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    Heat flux
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    Incompressible flow
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    Liquid films
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    Machinery
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    Mathematical models
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    Plasmas
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    Thermal evaporation
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    Thermal gradients
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    Two dimensional
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    Phase interfaces