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"while" command in UDF

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Old   February 27, 2004, 05:30
Default "while" command in UDF
  #1
wim vos
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hey you all, i'm modelling a user defined pressure outlet. in my model i have 4 different equations for the pressure (dependent on time). i tried to model it with a 'while' command. fluent compiles my C file but if i try to initialize fluent keeps on working (uses all possible memory of my computer, let it run over the night and still running)

i include my c-file so that u can see what i did. i hope that somebody can give me an answer.

thanks in advance

WIm

#include "udf.h"

DEFINE_PROFILE(outlet_snif1, thread, nv) { face_t f; real t = RP_Get_Real("flow-time");

begin_f_loop (f,thread)

{

do

{

F_PROFILE(f,thread,nv) = 0 * pow(t,0) + 0 * pow(t,1) - 7.615e+012 * pow(t,2) + 1.588e+012 * pow(t,3) - 1.371e+011 * pow(t,5) + 6.346e+009 * pow(t,6) - 1.708e+008 * pow(t,7) + 2.702e+006 * pow(t,8) - 2.383e+004 * pow(t,9) - 1.018 * pow(t,10);

}

while (t <= 5.133333333333333 * pow(10,-2));

do

{

F_PROFILE(f,thread,nv) = - 3.345e+004 * pow(t,0) + 6.08e+004 * pow(t,1) - 4.782e+004 * pow(t,2) + 2.131e+004 * pow(t,3) - 5915 * pow(t,5) + 1057 * pow(t,6) - 121.4 * pow(t,7) + 8.604 * pow(t,8) - 0.3407 * pow(t,9) - 94.82 * pow(t,10);

}

while (t <= 3.336666666666666 * pow(10,-1));

do

{

F_PROFILE(f,thread,nv) = 6.862e+012 * pow(t,0) - 8.426e+012 * pow(t,1) + 0 * pow(t,2) + 3.467e+012 * pow(t,3) + 0 * pow(t,5) - 2.062e+012 * pow(t,6) + 1.332e+012 * pow(t,7) - 3.89e+011 * pow(t,8) + 5.652e+010 * pow(t,9) - 3.326e+009 * pow(t,10);

}

while (t <= 3.843333333333333 * pow(10,-1));

do

{

F_PROFILE(f,thread,nv) = 3.723e+006 * pow(t,0) - 4.643e+006 * pow(t,1) + 0 * pow(t,2) + 0 * pow(t,3) + 4.662e+006 * pow(t,5) - 5.81e+006 * pow(t,6) + 3.217e+006 * pow(t,7) - 9.54e+005 * pow(t,8) + 1.485e+005 * pow(t,9) - 9587 * pow(t,10);

}

while (t > 3.843333333333333 * pow(10,-1));

} end_f_loop (f,thread) }
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Old   February 27, 2004, 10:58
Default Re: "while" command in UDF
  #2
Ale
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Hi Wim, remember that your UDF is executed before each iteration, and all cycles need to exit before going to the following iteration. If you use the do{}while cycle, checking the value of t, but not changing t in the body of the cycle, if t satisfies the condition once, it will satisfy it again and again, and the program will never exit the cycle.

I think you should replace the do{}while cycle with an if() control

I hope this helps.

Ale
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