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Sin function as a wall profile

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Old   March 21, 2013, 08:27
Default Sin function as a wall profile
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Hi all,

I want to create a wall surface as a sine function. Is it a good idea to create it via vertices with NURBS tool or can I use udf for telling Fluent that a straight line is actually a sine function?

Many thanks,

Musa
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Old   March 21, 2013, 11:52
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Quote:
Originally Posted by mozkan26 View Post
Hi all,

I want to create a wall surface as a sine function. Is it a good idea to create it via vertices with NURBS tool or can I use udf for telling Fluent that a straight line is actually a sine function?

Many thanks,

Musa
What do you think about Fluent
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Old   March 21, 2013, 12:14
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What do you think about Fluent
Sorry Far, couldn`t really get what you are telling.
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Old   March 21, 2013, 12:15
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Fluent cannot make changes at geometry level. so you have to make that sine wall in Gambit or any other preprocessor.
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Old   March 21, 2013, 12:20
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Quote:
Originally Posted by Far View Post
Fluent cannot make changes at geometry level. so you have to make that sine wall in Gambit or any other preprocessor.
Yes I know, you are right, sorry my first post may not really clear. I mean, is it a good approach to create a wall as a sine function with vertices by using NURBS tool in Gambit? Or can I do it with a udf file in Fluent. I am not really good at defining Boundary Profiles with UDF.
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Old   March 21, 2013, 12:21
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Easy method is gambit and I would always prefer it.
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Old   March 21, 2013, 12:22
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Easy method is gambit and I would always prefer it.
Thank you very much for your reply Far. I will try it in Gambit and hope I won`t face any meshing problem near surface.
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Old   March 27, 2013, 07:40
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Sorry to bring up this post again.

I am investigating a similar case. I have implemented the sinus-profile into FLUENT successfully.

Now I want to pose a non constant wall temperature at this boundary, using an UDF. I found several example scripts (in this case for a pressure profile), but they always assume one constant coordinate (BC is a straight line). In my case, the y coordinate is a function of the x coordinate. How can I implement this?

Example scipt for a "straight" BC:

#include "udf.h"
DEFINE_PROFILE(pressure_profile,t,i)
{
real x[ND_ND];
/* this will hold the position vector */
real y;
face_t f;
begin_f_loop(f,t)
{
F_CENTROID(x,f,t);
y = x[1];
F_PROFILE(f,t,i) = 1.1e5 - y*y/(.0745*.0745)*0.1e5;
}
end_f_loop(f,t)
}


Thank you in advance!
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Old   March 27, 2013, 07:47
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I am not expert in UDFs but just as a suggestion, what will happen if you change y=x[1] line with your y(x) sine function?
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Old   March 27, 2013, 08:02
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Quote:
Originally Posted by mozkan26 View Post
I am not expert in UDFs but just as a suggestion, what will happen if you change y=x[1] line with your y(x) sine function?
Well, this would help.

But what about

real x[ND_ND]; ?

My boundary has no constant x value...
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Old   March 27, 2013, 08:08
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Quote:
Originally Posted by j_h_86 View Post
Well, this would help.

But what about

real x[ND_ND]; ?

My boundary has no constant x value...
Oopps!! You are right. Here is where we need an expert. I wonder the answer too, it may help me at some point.
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Old   March 27, 2013, 12:55
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http://www.youtube.com/watch?v=U_z-Ufn0-kg
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Old   March 28, 2013, 11:58
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Quote:
Originally Posted by Far View Post
Dear Far,

could you link me to a tutorial, where a non-straight boundary is modelized in an UDF-file?

I am not into UDF a lot and tutorials seem to be very rare on the internet.

Best regards
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Old   March 28, 2013, 12:01
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The person who has created this video is also a forum member. You can contact him through youtube for futher details as I am not a UDF guy
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