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Old   July 19, 2012, 14:28
Default distinguish water and ice phases
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Esteban
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Hi everyone,

I'm working about 3D melting problem on fluent software.
I got the result of the simulation and for analyse I would like to measure the mass or volume of melting water
The problem is I need to distinguish water and ice, but i don't know how i can do it.

If you got an idea, let me know

Thank you
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Old   July 19, 2012, 15:24
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The "liquid fraction" is the variable you are serching for.

liquid fraction=1 -> Water
liquid fraction=0 -> Ice
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Old   July 20, 2012, 00:11
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first of all, thank you for your answer.

But as I work with water, it is a pure substance so Tliquidus = Tsolidus = melting temperature and the liquid fraction definition is : Beta=( T- T(solidus))/(T(liquidus)-T(solidus))
so, beta is not define so I can't use liquid definition.

I still got a distinguish problem. Have you an other idea to find a solution ?
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Old   July 20, 2012, 01:34
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I am also working with pure substances right now.
In this case, the liquid fraction is based on enthalpy. So it is still a variable to distinguish the solid and liquid phase and is well-defined even for pure substances.
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Old   July 20, 2012, 12:59
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So I don't need to give information about the solidus and liquidus temperature ?
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Old   July 20, 2012, 16:40
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Sure you need the two temperatures. The fluent manual tells you that you can model a pure substance just by entering two identical values for solidus and liquidus temperature.

Now imagine you heat the solid up to the liquidus temperature (which equals solidus). From now on, the liquid fraction is computed based on the enthalpy.
Lets say the enthalpy of fusion is 100 J/kg and at a certain time, we already put 40 J/kg of heat into the material at a constant temperature, then the liquid fraction is 0.4.

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Old   July 20, 2012, 18:29
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Yes, I agree with all you say.
So I launched a simulation with Tsolidus=Tliquidus=273.15K
After computational, I get these results

Temperature profil seems good, but the liquid fraction seems not good so I can't determine the volume of liquid fraction.

I don't know what stop me to figure out the right liquid fraction profile
Attached Images
File Type: jpg ice melting_temp profil.jpg (65.0 KB, 21 views)
File Type: jpg ice melting_liquid fraction.jpg (54.7 KB, 15 views)
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Old   July 20, 2012, 18:59
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This is really odd.
I ran lots of simulations with melting of a pure substance in fluent.
The liquid fraction was in excellent agreement with the temperature.

I can only assume that there is something wrong with your setup.
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