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3D velocity profile UDF

Hi guys

I would like to define a 3D velocity profile but I don't know how. I read lots of 2D examples, but I am still confused about 3D. Is there any one who can help me?
It is one of the samples for 2D How can I add the third dimension to this code?

The desired velocity is
Vz = (1-(x^2+y^2)/25)

#include "udf.h"

{
real x[ND_ND]; /* this will hold the position vector */
real y;
face_t f;

{
y = x[1];
F_PROFILE(f, thread, position) = 20. - y*y/(.0745*.0745)*20.;
}
}

 ghost82 November 17, 2012 05:46

1 Attachment(s)
Quote:
 Originally Posted by hadiCFD (Post 392629) Hi guys I would like to define a 3D velocity profile but I don't know how. I read lots of 2D examples, but I am still confused about 3D. Is there any one who can help me? It is one of the samples for 2D How can I add the third dimension to this code? The desired velocity is Vz = (1-(x^2+y^2)/25)

I think this should work:

Code:

```#include "udf.h" DEFINE_PROFILE(my_velocity, thread, position) {   face_t f;   real x[ND_ND];   begin_f_loop(f, thread)     {     F_CENTROID(x,f,t);     F_PROFILE(f, thread, position) = (1.-(x[0]*x[0]+x[1]*x[1])/25.);     }   end_f_loop(f, thread) }```
Verify the position of your geometry; as an example I centered a parallelepiped in 0,0,0.

Thank you ghost82
How can I verify the position of my geometry?

I upload my geometry. Thank you

http://s9.postimage.org/o9xptv5v3/Untitled1.jpg

 ghost82 November 18, 2012 10:03

1 Attachment(s)
Quote:
 Originally Posted by hadiCFD (Post 392775) Thank you ghost82 How can I verify the position of my geometry? I upload my geometry. Thank you
Imagine this simple example: a parallelepiped with its base centered in xy plane (figure on the left) and a parallelepiped not centered in the xy plane (figure on the right); imagine also that this base is the inlet velocity.

Your Vz velocity is a function of x and y coordinate, so each of the two cases will have different profiles, because x and y coordinates are different; according to this, you have to take into account the position of your inlet face in respect to the origin;

Eventually, you can translate your geometry in pre-processing, or alternatively you can modify your Vz formula, considering a translation transformation.

Daniele

 dragonship2011 December 4, 2012 02:32

ghost82,
I have a question to ask for you .In a non-regulation shape, for example ,ships , how can I get the center of gravity and buoyant coordinates in the Fluent software ?
Regards

 dragonship2011 December 4, 2012 02:32

Quote:
 Originally Posted by ghost82 (Post 392790) Imagine this simple example: a parallelepiped with its base centered in xy plane (figure on the left) and a parallelepiped not centered in the xy plane (figure on the right); imagine also that this base is the inlet velocity. Your Vz velocity is a function of x and y coordinate, so each of the two cases will have different profiles, because x and y coordinates are different; according to this, you have to take into account the position of your inlet face in respect to the origin; Eventually, you can translate your geometry in pre-processing, or alternatively you can modify your Vz formula, considering a translation transformation. Daniele
ghost82,
I have a question to ask for you .In a non-regulation shape, for example ,ships , how can I get the center of gravity and buoyant coordinates in the Fluent software ?
Regards

 ghost82 December 5, 2012 04:13

Quote:
 Originally Posted by dragonship2011 (Post 395606) ghost82, I have a question to ask for you .In a non-regulation shape, for example ,ships , how can I get the center of gravity and buoyant coordinates in the Fluent software ? Please help me. Regards
Hi,
specify in details your problem, you may better open a new thread.

 dragonship2011 December 5, 2012 06:39

Quote:
 Originally Posted by ghost82 (Post 395856) Hi, specify in details your problem, you may better open a new thread.
hi,thank you very much for reply. You know , A ship is running in the water,it is carried by buoyant .In the software of Fluent ,how can I get the center coordinate of buoyant .

 ghost82 December 5, 2012 10:16

Quote:
 Originally Posted by dragonship2011 (Post 395885) hi,thank you very much for reply. You know , A ship is running in the water,it is carried by buoyant .In the software of Fluent ,how can I get the center coordinate of buoyant .
ok understand, but unfortunately I haven't an answer..

 dragonship2011 December 5, 2012 20:29

Quote:
 Originally Posted by ghost82 (Post 395936) ok understand, but unfortunately I haven't an answer..
thank you all the same.

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