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please help UDF for velocity profile in y-directio |
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September 22, 2008, 06:58 |
please help UDF for velocity profile in y-directio
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#1 |
Guest
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hi everybody,
i want put parabolic velocity profile in a pipe flowing water.in verticle direction.means in y direction i want give parabolic profile so what should i do??what should i make in this program. there is a sample problem for x direction which is given in UDF manual /************************************************** ******************** udfexample.c UDF for specifying a steady-state velocity profile boundary condition ************************************************** ********************/ #include "udf.h" /* must be at the beginning of every UDF you write */ DEFINE_PROFILE(x_velocity,thread,index) { real x[ND_ND]; /* this will hold the position vector */ real y; face_t f; begin_f_loop(f,thread) /* loops over all faces in the thread passed in the DEFINE macro argument */ { F_CENTROID(x,f,thread); y = x[1]; F_PROFILE(f,thread,index) = 20. - y*y/(.0745*.0745)*20.; } end_f_loop(f,thread) } so what change should i make for y direction.i tried to put y at the place of x but it is not working. please help me. thank you |
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September 22, 2008, 12:29 |
Re: please help UDF for velocity profile in y-dire
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#2 |
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I think the problem lies in your DEFINE_PROFILE line. Try this:
#include "udf.h" DEFINE_PROFILE (y_velocity,thread,index) { real y,x[ND_ND]; face_t f; begin_f_loop(f,thread) { F_CENTROID(x,f,thread); y=X[1]; F_PROFILE(f,thread,index)=20.-y*y/(0.0745*0.0745) *20.; } end_f_loop(f,thread) } |
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September 22, 2008, 14:52 |
Re: please help UDF for velocity profile in y-dire
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#3 |
Guest
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thanks for response but keith still it is not giving parabolic profile in y direction...if you are understanding my problem please help me thank you.
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September 22, 2008, 16:36 |
Re: please help UDF for velocity profile in y-dire
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#4 |
Guest
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I apologize for committing an ID10T error in my previous post.
The best thing I can suggest is to read the documentation for the DEFINE_PROFILE section. There is an example of the DEFINE_PROFILE for a pressure boundary layer that explains what each section means. The y=x[1] gives the y coordinate of the centroid. You will need to replace the y=x[1] statement with the appropriate statement. |
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April 5, 2019, 07:08 |
defining temperature profile with UDF
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#5 |
New Member
soumya
Join Date: Apr 2019
Posts: 1
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I am facing same problem related to defining temperature profile in y-direction. @raju did you get any solution for your problem?? Thank you
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April 5, 2019, 10:58 |
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#6 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,741
Rep Power: 66 |
Follow the example in the manual. Replace x[0] with x[1].
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April 12, 2019, 23:21 |
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#7 |
New Member
Michael Fily
Join Date: Feb 2019
Posts: 24
Rep Power: 7 |
#include "udf.h"
DEFINE_PROFILE(log_velocity,thread,index) { real y[ND_ND]; real x,z; face_t f; begin_f_loop(f,thread) { F_CENTROID(y,f,thread); x = y[1]; z = y[2]; F_PROFILE(f,thread,index) = 26.22*log(x/2)/log(149.5/2); //Note here to express [28.19*log(x/2)/log(149.5/2)] in terms of (x,z); please get the //correct equation. } end_f_loop(f,thread) } ps/ it works for me in the 3d, try this one, change the fomular. This example with the change of velocity depending on the change of height (y-axis) |
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