Dynamics of Evaporating Films Under Reduced Gravity

Document Type

Conference Proceeding

Publication Date

1-9-2006

Department

Department of Mechanical Engineering-Engineering Mechanics

Abstract

Evaporation is a complicated fluid phenomenon involving the combined effects of several physical mechanisms including capillary- and gravity-induced interface instabilities, buoyancy, and thermocapillary flows, and vapor recoil deformation of the vapor-liquid interface. The combined effect of all these mechanisms leads to a complicated, three-dimensional fluid motion. Very little work has been done on establishing the fundamental fluid physics of film evaporation on liquid surfaces under reduced gravity conditions. A scaling approach has been used to determine the fastest growing wavelength on a perturbed isothermal vapor-liquid interface. For very thin liquid films, where gravitational effects are negligible and disjoining pressure forces are important, the fastest growing wavelength is proportional to the square of the initial mean film thickness. For thick liquid films, where gravitational effects are dominant, the fastest growing wavelength is independent of the initial mean film thickness and is proportional to the capillary length. A numerical approach based on finite difference techniques is used to analyze the isothermal film profile evolution equations. The findings from numerical analysis will be used to design the experimental test set up and define control parameters for the evaporation experiments to be conducted on NASA's Reduced Gravity Aircraft.

Publisher's Statement

Copyright 2006 by the American Institute of Aeronautics and Astronautics, Inc.

Publication Title

44th AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada

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