VOF with evaporation and condensation UDF's
 

Hello colleagues,

I have a question for those who know Fluent from its inside...

The VOF model theory states that only mass conservation equation is solved for secondary phases, therefore they called them the volume fraction conservation equations....At the end the primary phase volume fraction is the unity less the sum of secondary phases mass fractions....

So if I implement UDF to model evaporation and condensation (for example: water) mass sources, why should I have to write UDF for both cond/evap mass sources for primary phase if it is going to be calculated after volume fractions of secondary phases are done...


Best regards...

Can't you just use the evaporation-condensation option for mass transfer in the phase interaction toolbar instead of using a UDF?

When I use VOF, the evaporation-condensation option for mass transfer is available and can be used. I use Ansys Fluent 13. Maybe this option is not available in other versions of the software.

Hello guys I have a question : is the evaporation-condensation option work properly with VOF model?

Dear colleagues thanks for your answers....

I found this in the User's Guide...

1. evaporation-condensationenables you to apply the evaporation-condensation model as the mass transfer mechanism. This model is available with the mixture and Eulerian multiphase models. Refer to Evaporation-Condensation Model in the Theory Guide for a theoretical discussion about this model.
   

According to this the evaporation-condensation model is not available to be used with VOF simulations...I know you can select it from the User Inteface but it seems that it does not work....

Even if this is available or not, I'd like to consult the main question of my post which is what happens with the mass source calculated, by a UDF, for primary phases if no vof equation is solved for this one...

Best regards...and again thanks for your answers....

Dear gerardosrez thanks for illustration. About your question if you not use vof model so what model of multiphase flow you tried? furthermore selecting which of the phases be primary or secondary that is your choice and you can set any of the phases as primary or secondary as you like? I think your question seems obvious something?

kbaker