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Convective Effects During the Physical Vapor Transport Process. II - Thermosolutal ConvectionThe effect of an inert gas on the diffusive-convective physical vapor transport process is investigated for the case when the temperature gradient is stabilizing, and the concentration gradient destabilizing, for a wide parametric range. When an inert gas is present, the thermal and solutal convection oppose each other. The solutal field is destabilizing while the thermal field and the advective-diffusive flux stabilize the flow field. When the pressure of the inert component is increased, the stabilizing effect of the advective-diffusive flux is decreased; thus, convection becomes more vigorous. The nonlinear dynamics of the flow field here show a transition from quasi-periodic to chaotic state. When both stabilizing mechanisms are present, the flow field shows a transition to a steady state. Toward steady state, growth and amalgamation of rolls occur, which result in an overturning motion. This leads to a superposed flow consisting of one roll and a unidirectional flow. However, when the pressure is increased, the advective-diffusive stability mechanism is decreased. and oscillations of the flow field occur. The low gravity environment is effective at eliminating oscillatory behavior of the flow field and results in uniform temperature and concentration gradients.
Document ID
19930058427
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Duval, Walter M. B.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Journal of Materials Processing & Manufacturing Science
ISSN: 1061-0656
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
E-7190
Accession Number
93A42424
Distribution Limits
Public
Copyright
Other

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