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UDF for vapor pressure

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Old   May 18, 2017, 07:22
Default UDF for vapor pressure
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Anuja Vijayan
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Hello friends,
I have a temperature profile file (not udf but boundary profile in tabular form)as my wall BC. I thought my profile file is working fineas I get the expected Temperature change at wall from T plots after convergence. I have written a UDF to vary vapour pressure as a function of temperature. I have hooked it to the vapour pressure option while activating mass transfer from liquid to vapour>cavitation. It gets interpreted neatly and solution converges also.Now, the solution obtained is not showing the expected improvement (rather change) when compared to a case where Pv=const.
My UDF looks like this.

#include "udf.h"
/*for Vapour pressure*/
DEFINE_PROPERTY(Vapour_pressure,c,t)
{
real T = C_T(c,t);
real p_v;
p_v = (0.00329*exp(0.19039*T) - 0.05762)*1000000.0;
return p_v;
}

How will I know if this is working fine? Do I need to write the UDF specifically in terms of SUB_THREAD, SUPER_THREAD etc. I assumed that since I am calling UDF from vapour pressure options, it will take appropriately. Is that right?

To check if it is a problem with the UDF, I changed vapour pressure to a polynomial fit and temperature as explained before(as boundary profile)and tried. This is not working either. Now I doubt whether I can give Twall as boundary profile. How to confirm this? Fluent user's manual and udf manual are so abstract on this topic. Is there any source from which I can read more on boundary profile and udf for vapour pressure?
Has anybody done something similar? Any help is greatly appreciated.

PS:edited title and re-posted a previous thread material to get better visibility. Pardon me if it caused any inconvenience.
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Old   May 18, 2017, 09:28
Default vapour pressure change not accepted by Fluent
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Simulation_check1: Vapour pressure kept constant; energy equation switched ON with a UDF written for Twall.
Result: Predicted inlet temperature matched with experiment. Plotted wall temperature showed correct profile.
Simulation_Check2: Energy OFF; vapour pressure was assigned a real constant value using a UDF.
Result: Plotted pressure profile showed 3.5 bar inlet pressure instead of the expected 2.5 bar.
Simulation_check3: Enenry ON; Pv defined as piecewise linear.
Result: Plotted pressure profile showed 3.3 bar inlet pressure instead of the expected 2.5 bar.

Previously when vapour pressure was constant and Energy eqn OFF, I got the correct inlet pressure. The moment I change vapour pressure from constant value, something is going haywire. Any solution?
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Old   October 10, 2019, 04:21
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Dnyanesh Mirikar
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Did you able write correct UDF for vapor pressure? If you have, could you please share it with me? much appreciated. dnyansohm@gmail.com
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Old   October 21, 2019, 08:17
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Anuja Vijayan
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yes, I got the vapour pressure UDF correctly. I have sent that to you by email.
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Old   January 24, 2020, 20:08
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CWL
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Quote:
Originally Posted by anuarun View Post
yes, I got the vapour pressure UDF correctly. I have sent that to you by email.
I wonder if you would mind sharing your UDF function as well. I have been struggling of it.
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Old   February 4, 2020, 06:27
Default Vapour pressure udf
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Anuja Vijayan
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Please give your mail id.
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Old   May 20, 2020, 20:54
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Hyungyu Lee
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Quote:
Originally Posted by anuarun View Post
Please give your mail id.
Could you please share it with me? much appreciated

aerogyu@gmail.com
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Old   July 2, 2020, 20:59
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wugui Jiang
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Quote:
Originally Posted by anuarun View Post
Please give your mail id.
Could you send a copy to me. Thanks very much.

jiangwugui@gmail.com
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Old   July 14, 2020, 13:02
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Arun raj.S
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could you share the udf kindly. arunraj.v2009@gmail.com
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Old   March 3, 2021, 08:16
Default Vapour pressure udf
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hanzao
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Could you share this udf with me? My email is leo.insa.lyon@gmail.com
Thanks a lot
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Old   December 18, 2021, 05:57
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Would you be kind enough to send me this UDF? Here's my email:

Thanks!

Last edited by Jakubano; December 25, 2021 at 10:57.
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Old   December 23, 2021, 11:04
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please Could you share the udf with me ? thanks

My email is belkacemidjelloul@gmail.com
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Old   December 24, 2021, 10:12
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Whoever reads this and has this UDF, please post it below here. Otherwise, people will continue to post their email addresses here, and spammers will find them.

If after my message somebody still puts their email address below, those persons are not very smart.
__________________
"The UDF library you are trying to load (libudf) is not compiled for parallel use on the current platform" is NOT the error after compiling. It is the error after loading. To see compiler errors, look at your screen after you click "build".
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