# How to simulate the process of water evaporation by UDF?

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 April 1, 2010, 09:10 #2 New Member   beauty Join Date: Feb 2010 Posts: 27 Blog Entries: 1 Rep Power: 8 Hi! I'm learning on the problem as yours, do you have any experience to share? Thanks!

 April 1, 2010, 09:11 formula about evaporation! #3 New Member   beauty Join Date: Feb 2010 Posts: 27 Blog Entries: 1 Rep Power: 8 Hi! Have your problem solved? I'm interesting in the problem of evaporation as yours. After reading your programme, I have a question about the formula(m_dot_l = -(P_SAT-C_P(cell,sec_th))*sqrt(moleweight)*(2*pi*R*C_T(cel l,pri_th)), which literature include this? Looking forward to your reply! Thanks!

 April 5, 2010, 04:45 #4 Member   Robert Join Date: Feb 2010 Location: Germany Posts: 31 Rep Power: 8 Hi Why not using the cavitation-models, already included in FLUENT? You can use Singhal, Schnerr-Sauer and Zwart-Gerber-Belamri there. Greetings

April 6, 2010, 07:41
#5
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beauty
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Quote:
 Originally Posted by Robert@cfd Hi Why not using the cavitation-models, already included in FLUENT? You can use Singhal, Schnerr-Sauer and Zwart-Gerber-Belamri there. Greetings
Hi
Thank you for your suggestion. In my opinion, the mechanism of evaporation in the cavitation is different from flash evaporation. Maybe I am wrong, I will learn about the cavitation-models. Are you familiar with cavitation?

beauty

April 6, 2010, 08:31
#6
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Robert
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Hi
What is 'flash evaporation' ? You mean temperature-driven evaporation?

Quote:
 The water evaporation occurs as a result of the decrease of pressure in stead of temperature increasement.
In my opinion, thats the definition of cavitation, so you should take a closer look to the models.
If the pressure falls under a critical value, evaporation occurs. If the pressure is increasing downstream, the bubbles collapse (condensation) and locally you get really big values of temperature and pressure (its like an implosion).

Just look over the FLUENT user-guide or ask me again. Maybe I can help.

Greetings

 April 7, 2010, 22:38 #7 New Member   beauty Join Date: Feb 2010 Posts: 27 Blog Entries: 1 Rep Power: 8 Hi Flash evaporation is pressure-driven evaporation. When the saturated liquid (for example, liquid Hydrogen under high pressure) is released into atmosphere, most or all of the liquid immediately "flashes" into vapor, resulting in decrease of the system temperature. I wonder if the cavitation model can be helpful. Thanks Beauty

 August 25, 2010, 02:49 evaporation #8 New Member   Rana Join Date: Apr 2010 Posts: 10 Rep Power: 8 qiyang Is your's a constant temperature or varying temperature model, i need to write a udf for evaporation ocuring by means of decreasing pressure which in turn decreases the temperature. can u help me...

March 6, 2011, 02:48
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Quote:
 Originally Posted by Rana qiyang Is your's a constant temperature or varying temperature model, i need to write a udf for evaporation ocuring by means of decreasing pressure which in turn decreases the temperature. can u help me...
Hi,
Same question.
Any idea?

March 6, 2011, 02:58
#10
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Quote:
It has error: cell undefined in line 19
?

January 9, 2015, 14:59
Udf
#11
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Muhammed Asmail
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Quote:
did you reach to best solution?