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brusly September 5, 2006 06:01

boiling and condensation
hi all i am solving one heat pipe prolem includes condensation and boiling(phase change model).i want to know that which model is better and can i solve without udf.

advance thanks

Rajit September 5, 2006 18:40

Re: boiling and condensation
Hi brusly,

There is a tutorial on boiling.please have a look at it.

I think you can discrete phase model for this but you would be required to use an UDF to simulate the condensation since it is not automatically done in fluent.

All the best.



brusly September 6, 2006 01:03

Re: boiling and condensation
thanks ranjit

brusly September 6, 2006 01:09

Re: boiling and condensation
i am not able to get the tuitorials.plz anyone having the tutorial.

advance thanks

Rajit September 6, 2006 18:58

Re: boiling and condensation
Hi Brusly,

Please forward me your personal mail id. I will post the tutorial for you.



greg September 7, 2006 00:08

Re: boiling and condensation
if there is a free surface in heat pipe (is there) why not use a VOF model??

Asghari September 7, 2006 00:33

Re: boiling and condensation
Hello, Rajit

I am working on two phase flow with phase change,also.Please ,If it is possible for you send me toturial file.My email address is :

Thanks in advance.

brusly September 7, 2006 00:42

Re: to ranjit
hai ranjit this is brusly my id is thanks a lot

ravi September 7, 2006 00:47

Re: boiling and condensation
hi rajit, im also working on chill down problem (2 phase flow) can u send me the tutorials, my email id is thanks in advance. bye

brusly September 7, 2006 00:47

Re: boiling and condensation
hi greg

i have model a circular pipe,outer surface were divided in to 3 surfaces evoporator,adiabatic section,condensor like wise ,inside in the evoporator section boiling takeplace and in the condensor part codensation will be takeplace

ia it possible with vof

thank u

Asghari September 7, 2006 03:53

Re: boiling and condensation

Thank you very much for sending tutorial files, but i have a question from you:

Is this udf used for evaporation and condensation,synchronously ?

Thanks for your response;


greg September 7, 2006 05:24

Re: boiling and condensation
hi In my opinion one toutorial can be use for boiling and condensation and evaporation. Everything depends of temperature. You can set up an equation (or if else statement) that evapoarion can take place below boiling point and evapoarion over it. The Define_mass_transfer is so kind of macro that you can define from which phase to which phase mass transfer can be. Boiling from liquid to gas and condensation from gas to liquid. I never done a condensation but I think it is possible. Please let me know if I`m wrong. good luck

brusly September 7, 2006 22:21

Re: boiling and condensation
thank u i will try it

greg September 8, 2006 11:24

Re: boiling and condensation
hi I have on probblem with this boiling. using standard (provided by Fluent) tutorials - means udf`s I can get boiling of water (both in VOF and Mixture model) but.... the temperatures are stupid. In liquid pase temperature is OK but in gas phase it reach maximum or minimum temperature (1K or 5000K which are max and min. temperatures in FLUENT). Do yuo happen to know what to do? Meybe you had the same problem. regards g

misiu September 11, 2006 06:30

Re: boiling and condensation
hej Greg! This problem with Temp. min or max in Fluent, is normal, You must change value in equation, on conference I listen aboaut this problem

greg September 12, 2006 01:50

Re: boiling and condensation
oooo You made me to belive it can be solved. :)

"You must change value in equation, on conference I listen aboaut this problem "

In my equation (put by me inside the udf)?? When I will change the value in my equation than I will change the results (isn`t it??). You mean value in which equation? In UDF there isn`t many values: relaxation time (0,1s - constant) and the rest of the values are values like temperature, density or volume. can you provide me more clues. Thank you for hope :))))

greg September 12, 2006 06:08

Re: boiling and condensation
Misiu are you from Poland?? Meybe you have any papers (descrabing my problem) from this conference you are talking aboute and you are able to send it to me?


misiek September 13, 2006 04:31

Re: boiling and condensation
Yeea I`m from Polska (Poland) Technology University I haven`t any information about "this" problem, only to hear about min and max temperature in proccessing boiling in Fluent. Perhaps You must change boundary steady or unsteady condition Best regards

greg September 13, 2006 05:39

Re: boiling and condensation
ok I will try. Misiek sounds fimiliar for me so I asked. Something like teddy bear

Mohammad September 19, 2006 13:55

Re: boiling and condensation
Rajit, Would u plz email the tutorial to me. I have also the same problem with boiling.

Mohammad My email address is mhfd39 @ Y!

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