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Old   February 1, 2012, 23:59
Default Boiling and Condensation
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Ghaleb
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I need to model boiling and condensation at the same time in a 2D domain. Imagine three separate blocks on top of each other I have the bottom block is full with initially water, the middle block is solid and the top block will be initially vapor. there is a positive heat flux on the bottom edge of the bottom block and a negative upper edge on the top block. I am using Euler-Euler (with boiling model in Fluent 13) and the built in mass transfer mechanism (water to vapor Tsat 373.15). I have tried different initialization and still got same problem; I always initialize near the saturation temperature for both water and vapor and then I patch the top block to vapor (volume fraction of vapor 1) and patch temperature somewhere close above the saturation temperature.

when I run the solution and looking at the monitors of pressure on the vapor side i notice that pressure increases to unrealistic value (`1200 MPa) and it never decreases and still on the pressure some phase change from vapor to liquid occurs. I have been trying to solve the issue of the really high pressure for long time now and still couldn't; while at the bottom block pressure looks fine.
What makes me confident that I am on the right track is when I try condensation alone on the same model and I keep the problem setup the same I only define the bottom block as solid (no more boiling) the pressure on the condensation side will fluctuate around realistic values (`1000 Pa) and it decreases as soon as phase change starts (from vapor to liquid). And I have also tried boiling alone it worked fine.

I would appreciate any suggestions to solve this problem, thank you in advance.

Ghaleb Sater
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