August 13, 2020 at 9:07 pmAjayc1160Subscriber
I am trying to simulate condensation of mixture of water vapor(0.025 mass fraction) and air @ 300K,27C ,1m/s coming in contact with cooling coils at constant temp of 283K. To perform this in fluent i used following 2 different scenarios
1)Using Mixture Eulerian model with built in condensation model (Lee model)
One phase is mixture of air and water vapor
Another phase is only water liquid . Condensation is then defined using mass transfer mechanism and I defined a custom function for setting saturation temperature depending on vapor pressure with UDF
Use species model physics , euler mixture and species transport model. Use two different mixtures , one phase is mixture of air and water vapor, the other phase is species mixture consisting of only liquid. I define mass transfer using species mass transfer model and saturation pressure is modified as function of temperature .
In both of these scenarios, the simulation diverges after 2nd iteration. I m attaching error due to divergence from both of these case belowAugust 13, 2020 at 9:10 pmAugust 14, 2020 at 9:15 amRobForum ModeratorDoes the model run single phase? Strip out all the complex parts and work up: this helps you check for errors but also focuses attention to the section/model setting that fails.
August 14, 2020 at 12:47 pmAjayc1160SubscriberHi Rob
The model runs well when i create air and vapor as two different phases instead of using them as mixture.
August 14, 2020 at 1:04 pmAjayc1160SubscriberIn addition to this, to answer your question previously, yes, the model runs good for only single phase like air . I removed the phase change and have only air passing through the channel. It works fine
August 14, 2020 at 1:18 pmAjayc1160SubscriberIn addition, I see that when i run the model with mixture of air and vapor without any phase change,then the model works fine too. So the divergence has to do something with phase change
August 14, 2020 at 2:50 pmRobForum ModeratorOK, so what would cause a sudden failure with phase change? How humid is the air if you run the system single phase?
October 25, 2020 at 3:14 amAjayc1160SubscriberNot sure what is causing this divergence with phase change. May be there is very high rate of condensation
October 26, 2020 at 12:02 pmRobForum ModeratorPossibly. If air & vapour are different phases it's a different problem and you won't have a saturation value. If you alter the temperature so you're above the dew point does it run?
November 23, 2020 at 6:19 amAjayc1160SubscriberHi Rob. Im dicussing this problem on https://forum.ansys.com/discussion/15997/providing-0-mass-fraction-in-vaccum-condition#latest. I have added my latest comments there
November 23, 2020 at 6:19 amAjayc1160Subscriber
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