Hey Olivier, It seems like this is a phase separation problem. One option is to try to model infinitesimal moving interfaces as you seem to be thinking now, with some sort of Stefan condition to dictate their motion. However, another approach which is useful in modeling phase separating systems is to start with a Cahn-Hilliard style equation to model the dynamics of phase separation. Have a look at the Phase Field examples, which show some phase separation using what are referred to as "non-conserved" order parameters (e.g. a parameter that goes from 0 if liquid to 1 if solid). Then, consider the Cahn-Hilliard examples, including " http://www.ctcms.nist.gov/fipy/examples/cahnHilliard/generated/examples.cahnHilliard.mesh2D.html";, which is an alternate implementation of the first Cahn-Hilliard example (it's linked to via an image on the main FiPy page, but seems not to be included in the main Examples page...?). Cahn-Hilliard equations are designed to model a "conserved" order parameter, such as concentration of a species, which is more what you're considering.
Best, Ray On Wed, Dec 11, 2013 at 10:50 AM, Olivier DEZELLUS < [email protected]> wrote: > Hello, > > I am a completely newbie in the use of FiPy but I tried to understand by > using the different examples and particularly the ones on diffusion > problems. However without any success sinces several weeks... this is the > reason of my email to the list to find some help from more qualified > users... > > My diffusion problem is summarized in the attached pdf file. > > - An alpha(mostly A with a limited solubility of B)+beta(pure B) alloy > is in contact with a third element and a reaction occurs. > - The thickening of the tau reaction layer, that is rich in element B, > induces a depletion in B of the two phase layer > - Depletion in B leads to the formation of a pure alpha layer > - As the process continues, tau and alpha layers thickens > > From experimental study I have the rate of growth (constants Ktau and Kas) > of the Tau and alpha layers. > > I would like to know if this diffusion process could be simulated by using > FiPy ? The quantity I am interested in is the concentration in B at the > left hand side of the alpha layer, at interface with the tau layer. > > I tried to simplify the problem by using only one moving boundary (the > alpha/alpha+beta) and giving a flux condition on the tau/alpha interface bu > without any success. > > Does anyone have an idea on how to model this in FiPy ? > > Regards, > Olivier > > > -- > > ----------------------------------------------------------------- > La France est en 5e position pour le nombre de publications et en 26e pour le > financement de la recherche académique. > Notre système de recherche est-il inefficace ou insuffisamment financé ? > http://recherche-en-danger.apinc.org/ > > ------------------------------------------------------------------ > Dr Olivier DEZELLUS > Laboratoire des Multimatériaux et Interfaces (UMR 5615)http://lmi.cnrs.fr/ > 43, Bd du 11 Novembre 1918 > 69622 Villeurbanne Cedex > Tel: 04 72 44 83 86 > Fax: 04 72 44 06 18 > > > > _______________________________________________ > fipy mailing list > [email protected] > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] > >
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