Diffuse interface tracking of immiscible fluids : improving phase continuity through free energy density selection

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DOIResolve DOI: http://doi.org/10.1016/j.ijmultiphaseflow.2011.02.002
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TypeArticle
Journal titleInternational Journal of Multiphase Flow
Volume37
Pages777787; # of pages: 11
Subjectdiffuse-interface method; phase-field; interface tracking; Cahn-Hilliard free energy theory; continuity; spontaneous drop shrinkage; critical drop radius
AbstractDiffuse interface (DI) tracking methods adopt the double-well energy density function to describe the free energy variation across an interface, leading to phase interpenetration and spontaneous drop shrinkage when applied to immiscible two-phase systems. While the observed continuity losses can be limited by constraints placed on the interfacial width and mobility parameter, the associated increase in computational cost and mesh requirements has limited DI methods to 2D planar and axi-symmetric flow. Using the proposed temperature-variant simplified energy density function (TVSED), the effect of the metastable thermodynamic region on phase continuity is examined using a reduced temperature parameter, Tg. The solutions obtained by the proposed DI implementation and a volume-of-fluid (VOF) based solver are discussed for two common benchmark simulations (collapse of a column of water, and droplet deformation/relaxation in simple shear). While comparable solutions are obtained from the Tg=0 and VOF simulations; the large metastable region of the more commonly used double-well function (Tg=1) promoted inter-mixing in the bulk phases, diluting the inertia transferred between impacting fluids and under-predicting deformation in shear. The fundamental mechanisms responsible for spontaneous drop shrinkage are eliminated at Tr=0, allowing for constraints on the interfacial width and mobility to be relaxed. The comparable performance of Tg=0 and VOF simlulations is a promising indication of the potential for application to complex 3D flows at reduced mesh resolution relative to existing DI methods.
Publication date
LanguageEnglish
AffiliationNRC Institute for Chemical Process and Environmental Technology; National Research Council Canada
Peer reviewedYes
NRC number52854
NPARC number19554414
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Record identifier43fdc6f4-70c8-42df-9f15-caf46c4e6c1a
Record created2012-02-24
Record modified2016-05-09
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