Evaporation with population balance model

lihuang · July 19, 2011, 12:19

Dear friends,

I have been modeling water droplets evaporation with Population Balance Model. My problem is that particle volume fraction does not converge very nicely, although overall mass is well balanced.

In my case, I use mixture model. Mass transfer from liquid drops to vapor phase (air+water vapor) is defined through DEFINE_MASS_TRANSFER. At the same time, changes in liquid drop's diameters is defined through DEFINE_PB_GROWTH_RATE. Residual plots are generally good for all other parameters than volume fraction of liquid particles (to only about 0.1 level).

Shall I also introduce source of energy and/or momentum to the mixture phase and source of particle volume fraction to particle phase to get nicely converged results?
Thanks for your suggestions.

vaibhavraikhare · January 28, 2012, 11:27

Sir,
i am working on same problem of yours. i also used mixture model and discrete model for population balance model.how can i give the nucleation rate and growth rate in this model for water vapor. and if you can tell what is the concept of Min and Max Bin size. How it can be defined.? help if you plzz...

lihuang · January 28, 2012, 22:50

Both rates were defined in Udfs. Or you can set constant rate. If you are using fluent 13.0, you need to click the phenomena option under PBM settings window to make changes on nuclear ion rate.

lihuang · January 28, 2012, 22:56

The min and max bin size are defined in the PBM settings window. You can check out the theory's guide for the calculation of each bin between min and max bins. You can also print out all bin size by one click there. Good luck

vaibhavraikhare · February 5, 2012, 01:19

Dear Lihuang,
i am still not getting my results, volume fraction does not converge..as there might be some problem in PBM or UDF. Can you tell me if i want to give the constant mass transfer value for it what it will be??? and i haven't found any UDF for PBM to specify the growth rate and nucleation rate.

July 19, 2011, 12:19	Evaporation with population balance model	#1
lihuang Member Li Huang Join Date: Jan 2011 Posts: 30 Rep Power: 15	Dear friends, I have been modeling water droplets evaporation with Population Balance Model. My problem is that particle volume fraction does not converge very nicely, although overall mass is well balanced. In my case, I use mixture model. Mass transfer from liquid drops to vapor phase (air+water vapor) is defined through DEFINE_MASS_TRANSFER. At the same time, changes in liquid drop's diameters is defined through DEFINE_PB_GROWTH_RATE. Residual plots are generally good for all other parameters than volume fraction of liquid particles (to only about 0.1 level). Shall I also introduce source of energy and/or momentum to the mixture phase and source of particle volume fraction to particle phase to get nicely converged results? Thanks for your suggestions.

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January 28, 2012, 11:27		#2
vaibhavraikhare Member Vaibhav Rai Khare Join Date: Jul 2011 Location: Jaipur Posts: 37 Rep Power: 15	Sir, i am working on same problem of yours. i also used mixture model and discrete model for population balance model.how can i give the nucleation rate and growth rate in this model for water vapor. and if you can tell what is the concept of Min and Max Bin size. How it can be defined.? help if you plzz...

January 28, 2012, 22:50		#3
lihuang Member Li Huang Join Date: Jan 2011 Posts: 30 Rep Power: 15	Both rates were defined in Udfs. Or you can set constant rate. If you are using fluent 13.0, you need to click the phenomena option under PBM settings window to make changes on nuclear ion rate.

January 28, 2012, 22:56		#4
lihuang Member Li Huang Join Date: Jan 2011 Posts: 30 Rep Power: 15	The min and max bin size are defined in the PBM settings window. You can check out the theory's guide for the calculation of each bin between min and max bins. You can also print out all bin size by one click there. Good luck

February 5, 2012, 01:19		#5
vaibhavraikhare Member Vaibhav Rai Khare Join Date: Jul 2011 Location: Jaipur Posts: 37 Rep Power: 15	Dear Lihuang, i am still not getting my results, volume fraction does not converge..as there might be some problem in PBM or UDF. Can you tell me if i want to give the constant mass transfer value for it what it will be??? and i haven't found any UDF for PBM to specify the growth rate and nucleation rate.