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Crystal September 16, 2004 22:16

Using UDF in VOF model for Condensation
Hi I'm trying to use VOF in fluent to model the condensation of vapor in groove. Since heat and mass transfer occur during the phase change,I must add the mass source term in VOF equation and the heat source term in Energy equation.I'm a greenhand in this field,can anybody be so kind to give me some advices? And if you got some case or source program of VOF-UDF for modeling liquid-vapor phase change program ,could you send me one? Thanks a lot and best regard!

yours, Crystal

prasanth September 17, 2004 07:25

Re: Using UDF in VOF model for Condensation
Dear sir,

If you get fruitful response to your query, I would be the happy person. One thing , why are you choosing VOF over mxture model?

regards prasanth

Aravind September 17, 2004 11:20

Re: Using UDF in VOF model for Condensation
Hi Crystal,

If you/your school has the licence of Fluent, then you can go to the following website Here there are lot of examples in VOF module. Also you can download .msh, .cas files and most importantly .c or UDF files. There is an example on Boiling heat transfer in this website, where a UDF for mass transfer calculation is provided. Take a look at it, may be you can develop your own for condensation. In that case let me know, it might be helpful to me.

regards, Aravind

Crystal September 20, 2004 04:33

Re: Using UDF in VOF model for Condensation
Dear Aravind ,

Thank you fot your help!

I will go to have a look.

best regard!

yours, Crystal

Crystal September 20, 2004 04:44

Re: Using UDF in VOF model for Condensation
Dear prasanth,

I choose VOF rather than mixture model, because in my problem, the liquid-vapor interface is clear,which si also what we focus in. in addtion, I have refered to one of Dr. Faghri's paper,the problem introduced in the paper is similar to mine. He adopted VOF model and solve the problem successfully, but he did not give the detail about the operating process using FLUENT. I hope I could solve my problem by using the same method.

yours, Miss Crystal :>

prasanth September 22, 2004 18:56

Re: Using UDF in VOF model for Condensation
Dear crystal,

Can you give the reference for Faghri's paper here or to my mail id:

I asked about mixture model becuase, mixture model is more suitable for interpenetrating fluids!! condensation means there will conversion of vapor to liquid. I am already using similar kind of UDF suggested by aravind for my evaporation problem. but i am having doubt with the time relaxation factor "0,1" used in the UDF? and also some others..

with regards and best wishes!! prasanth

Aravind September 26, 2004 18:08

Re: Using UDF in VOF model for Condensation
Hi Crystal and Prasanth,

It would be great if you could let me know if you guys could tell me what needs to be changed in the boiling UDF to apply it to a condensation problem? I went through that code, but couldn't understand anything physical in that!

Thanks, Aravind

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