solidificationMeltingSource: Improved documentation

Patch contributed by Lorenzo Trevisan
Resolves patch request https://bugs.openfoam.org/view.php?id=2932
This commit is contained in:
Henry Weller
2018-05-14 17:23:34 +01:00
parent d030bb35c3
commit e57a62b400

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@ -31,10 +31,28 @@ Description
The isotherm phase change occurs at the melting temperature, \c Tsol (= \c
Tliq). The not isotherm phase change occurs between solidus and liquidus
temperature, \c Tsol < \c Tliq respectively, as long as the melt fraction is
greater than the max eutectic melt fraction, \c alpha1e (0 =
pure_substance, 1 = eutectic_mixture is not permitted) , i.e. eutectic to
initial solvent concentration difference, where a linear eutectic melt
fraction to temperature relation is considered - lever rule.
greater than the max eutectic melt fraction, \c alpha1e (0 = pure_substance,
1 = eutectic_mixture is not permitted), where a linear eutectic melt
fraction to temperature relation is considered; e.g. given a specific
quantity of a binary system, \c alpha1 is its melt fraction and \c alpha0 is
its solid fraction, such that \c alpha0 = 1 - \c alpha1 therefore, assuming
infinite solute diffusion, the quantity of a component in solid phase is (1
- \c alpha1) * \c CS where \c CS is the solid concentration of the
considered component and the quantity of a component in liquid phase is \c
alpha1 * \c CL where \c CL is the melt concentration of the considered
component; considering that the total quantity of a component must be equal
to the sum of the quantities of the considered component in the liquid and
solid phases, if \c C0 is the initial concentration of the considered
component before the phase change, then:
\c C0 = (1 - \c alpha1) * \c CS + \c alpha1 * \c CL (lever rule)
from which: \c alpha1 = (\c C0 - \c CS) / (\c CL - \c CS)
and thus:
- for a miscible binary system \c alpha1e = 0;
- for a binary system not miscible at solid state
\c alpha1e = \c C0 / \c CLE where \c CLE is eutectic melt concentration;
- for a binary system partially-miscible at solid state
\c alpha1e = (\c C0 - \c CSE) / (\c CLE - \c CSE) where CSE is eutectic
solid concentration of the relative solid solution.
The presence of the solid phase in the flow field is incorporated into the
model as a momentum porosity contribution; the energy associated with the