Extract primary phase thread in VOF with 3 phases
 

Dear Fluent users , I am using VOF model with 3 phases , one primary phase and 2 secondary phases, I need to extract (retrieve) the primary phase thread ..I try to use THREAD_SUB_THREAD ..it work for 2phase vof model (one secondary phase) ..but it not work for the case of 3 phases...

I need to retrieve the thread of the PRIMARY PHASE ...I read in the manual that : If you have more that one secondary phase for your multiphase model,you will need to use the PHASE_DOMAIN_INDEX utility to retrieve the corresponding phase_domain_index for the given domain..

please could some body give me any help about using this macro for 3 phases VOF model... thanks in advance , Eric

Re: Extract primary phase thread in VOF with 3 pha
 

Here is what I could find in the advanced UDF training handouts:

"Each phase has a phase_domain_index. The phase_domain_index is 0 for the primary phase and N-1 for the last secondary phase."

Therefore, this is what I think is applicable to your 3 phase system:

1st phase = primary phase => phase_domain_index for this phase is 0

2nd phase = 1st secondary phase => phase domain_index for this phase is 1

3rd phase = 2nd secondary phase OR last secondary phase => phase_domain_index for this phase is 2.

This checks out with the instructions stated above. For instance, if N (which I assume refers to the total number of phases) is 3, => the phase _domain_index for the last secondary phase is N - 1 = 3 - 1 = 2.

Hope this helps.

hi eric..i want to clear defining whats you've been directly talking about, so if we want to modelling for example gas-oil-water separator we have to use that UDF (extract the primary phase thread??is that different from "patch" in FLUENT??)