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-   -   phase change (http://www.cfd-online.com/Forums/fluent/31517-phase-change.html)

rookie May 21, 2003 14:53

phase change
 
Hello All,

In DPM case, the discrete phase is liquid water and one of species in the continuous phase is vapor water. To my understanding, liquid water can be converted to vapor water by evaporating (Fluent has a marco for it). I am not sure if the specie vapor water can be condensed to liquid water (discrete phase)? If possible, do i need write some UDFs? Which Marcos?

Thank you!

prasanth May 22, 2003 08:18

Re: phase change
 
hi Rookie, I think my problem is somewhat similar to you. mine is a closed cylindrical tank in which liquid hydrogen is partially filled(cryogenic propellant tank). Now, since the liquid will be stored at 20k,there will be heat leakage into the tank. so there has to be evaporation from liquid to the ullage space... I am solving this problem in fluent using VOF model and there is no option for evaporation..so presently i am trying using UDF for mass transfer at phase interaction panel. I am struggling to come out with a perfect equation including vapor pressure. So can you help me in this regard. thanks in advance prasanth

Mahesh May 22, 2003 10:33

Re: phase change
 
hi rookie,

Is the temperature in the domain is going below saturation temp. of water? Then in that case, you have to add mass source term for water and mass sink term for vapor phase.


rookie June 12, 2003 20:47

Re: phase change
 
Thank you! prasanth and Mahesh,

At the beginning, I thought in Mahesh's way. But it is not easy to implement. I found an example that may help UDF manual6.1 section 4.6.12. I will let you guys know what comes up.

Rookie


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