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-   -   UDF for inlet velocity profile (http://www.cfd-online.com/Forums/fluent-udf/111773-udf-inlet-velocity-profile.html)

Bollonga January 15, 2013 06:22

UDF for inlet velocity profile
 
2 Attachment(s)
Hi guys,

I'm using a UDF for a velocity profile to define the atmospheric boundary layer in a 2D problem. I've used the attached c code as explained in the user manual, apparently it's interpreted properly but results don't show any influence on the profile, it appears to be just a uniform velocity at the inlet (see attached picture for 5s).

1) Which can be the problem? Is there something wrong in the code?

2) What will happen if I modify the ymax coord in the code so it's higher than the domains's ymax?

3) Also I would like to use a profile for the turbulence intensity (TI), but Fluent only allows me to use it for k and epsilon. Is there a way to use TI and Turbulent Length Scale (TLS) instead of applying the formulae for (TI,TLS)\Rightarrow(k,epsilon).

4) I will need to apply the same profile to a 3D case. It will be exactly the same in the x-y plane and constant in the z-direction. Can I use directly the same code? If not, what do I have to modify?

Thanks you all!

Env October 6, 2015 12:53

TI Profile
 
Hello Bollonga: I have same problems as yours, and I see that you asked this question long time ago! so I assume you have found the answers although no one replied here. I appreciate if you could share what you found with me. My main problem is how to write a UDF to use a profile for TI of an inlet boundary condition.

If you have an example UDF, I appreciate if you share it here.

Thanks,
Env

Quote:

Originally Posted by Bollonga (Post 401913)
Hi guys,

I'm using a UDF for a velocity profile to define the atmospheric boundary layer in a 2D problem. I've used the attached c code as explained in the user manual, apparently it's interpreted properly but results don't show any influence on the profile, it appears to be just a uniform velocity at the inlet (see attached picture for 5s).

1) Which can be the problem? Is there something wrong in the code?

2) What will happen if I modify the ymax coord in the code so it's higher than the domains's ymax?

3) Also I would like to use a profile for the turbulence intensity (TI), but Fluent only allows me to use it for k and epsilon. Is there a way to use TI and Turbulent Length Scale (TLS) instead of applying the formulae for (TI,TLS)\Rightarrow(k,epsilon).

4) I will need to apply the same profile to a 3D case. It will be exactly the same in the x-y plane and constant in the z-direction. Can I use directly the same code? If not, what do I have to modify?

Thanks you all!



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