modelling evaporation-condensation in closed system

alimondegari · October 12, 2013, 12:07

hi
i am modelling a two-phase flow for water liquid and vapor in steady state in a closed system . it contains evaporation and condensation. is using VOF right for this case ? i fill half of the system with water in initialization but after some iteration total mass of system decrease significantly and continuity equation never converge . what's the reason ?
please help me
thanks

aminem · February 6, 2014, 09:17

I try to simulate the same problem. I use a mixture model with tree phase (air, liquid, vapor). After few iterations I have this message: # Divergence detected in AMG solver. I had try to change the under relaxation value, but is diverge as well.

aminem · February 20, 2014, 13:08

Hi
You must use a transient solver for a good convergence.
I used a coupled scheme with flow number of 50I used 0.001 s time step to have stable convergence
Good luck

xiaobingwill · April 25, 2014, 01:09

Hi guys,
I'm doing similar problems right now. So did you use Fluent evaporation-condensation model to do the calculation or wrote your own udf for the simulation?

xiaobingwill · April 25, 2014, 01:20

Hi guys,

In my view, if you use VOF to do this simulation, you should write UDF by yourself for the eva-conden process. But if you turn to Mixture model, you can use the written model.

October 12, 2013, 12:07	modelling evaporation-condensation in closed system	#1
alimondegari New Member ali mondegari Join Date: Oct 2013 Posts: 3 Rep Power: 13	hi i am modelling a two-phase flow for water liquid and vapor in steady state in a closed system . it contains evaporation and condensation. is using VOF right for this case ? i fill half of the system with water in initialization but after some iteration total mass of system decrease significantly and continuity equation never converge . what's the reason ? please help me thanks aamev likes this.

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February 6, 2014, 09:17		#2
aminem Member amine Join Date: Jan 2014 Location: FRANCE Posts: 84 Rep Power: 12	I try to simulate the same problem. I use a mixture model with tree phase (air, liquid, vapor). After few iterations I have this message: # Divergence detected in AMG solver. I had try to change the under relaxation value, but is diverge as well.

February 20, 2014, 13:08		#3
aminem Member amine Join Date: Jan 2014 Location: FRANCE Posts: 84 Rep Power: 12	Hi You must use a transient solver for a good convergence. I used a coupled scheme with flow number of 50I used 0.001 s time step to have stable convergence Good luck

April 25, 2014, 01:09		#4
xiaobingwill New Member Xiaobing Zhang Join Date: Apr 2014 Posts: 12 Rep Power: 12	Hi guys, I'm doing similar problems right now. So did you use Fluent evaporation-condensation model to do the calculation or wrote your own udf for the simulation?

April 25, 2014, 01:20		#5
xiaobingwill New Member Xiaobing Zhang Join Date: Apr 2014 Posts: 12 Rep Power: 12	Hi guys, In my view, if you use VOF to do this simulation, you should write UDF by yourself for the eva-conden process. But if you turn to Mixture model, you can use the written model.