[amir_14]

Hi dear friend
I wrote a udf code to add a momentum source on flow around my airfoil,but it has no effect on my solution.

#include "udf.h"
DEFINE_SOURCE(my_source,c,t,dS,eqn)
{
/* Declare Variables */
real xc[ND_ND];
real source, x, y;
real m1, m2;
real b_bottom, b_left, b_top, b_right;
real check_bottom, check_left, check_top, check_right;
/* Call x and y data from FLUENT */
C_CENTROID(xc,c,t);
x=xc[0];
y=xc[1];
/* Define region. Four inequalities are used to define the rectangular region. */
m1=0.5250;
m2=-1.9048;
b_bottom=0.0089;
b_left=0.0575;
b_top=0.0090;
b_right=0.0790;
check_bottom=m1*x+b_bottom;
check_left=m2*x+b_left;
check_top=m1*x+b_top;
check_right=m2*x+b_right;
/* Apply source term to region inside the four inequalities */
if ((y>=check_bottom)&&(y>=check_left)&&(y<=check_top)&&(y<=check_right))
{
source = 1000.0;
dS[eqn] = 0;
}
else
{
source = 0;
dS[eqn] = 0;
}
C_UDMI(c,t,0)=source;
return source;
}

Can everybody help me about this ?

[diamondx]

I'm not an expert, please look at this thread : http://www.cfd-online.com/Forums/flu...g-happens.html

I hope it can solve your problem...

[amir_14]

Originally Posted by diamondx

I'm not an expert, please look at this thread : http://www.cfd-online.com/Forums/flu...g-happens.html

I hope it can solve your problem...

hi dear M. Ali
tanx for your answer
i have some question about this (PLZ)
1.my mesh is not enough fine and i should adapt mesh near airfoil's wall to be cell centroids within the ranges. Is this wrong?
2.you increase the amount of source from 1000 to 10000.Why?

[diamondx]

back in those days i didn't know the magnitude of the value of the source i was giving. i wa thinking that may be 1000 will do nothing to my flow...
Try playing a little bit with your bottom left right limits, see if it can changes the solution

[amir_14]

Originally Posted by diamondx

back in those days i didn't know the magnitude of the value of the source i was giving. i wa thinking that may be 1000 will do nothing to my flow...
Try playing a little bit with your bottom left right limits, see if it can changes the solution

can you help me about Number of User-Defined Memory Locations ?
Is it important?

[diamondx]

no, where do you see that. did you follow the tutorial about UDF integration ???
It can really help

[amir_14]

Originally Posted by diamondx

no, where do you see that. did you follow the tutorial about UDF integration ???
It can really help

it is necessary because of C_UDMI but i don't know number of this

[diamondx]

are talking about the zero in the C_UDMI

[amir_14]

Originally Posted by diamondx

are talking about the zero in the C_UDMI

yes
without change of this in define menu i have an error at ansys running
when i define 1 for Number of User-Defined Memory Locations run will start

[amir_14]

Dear Ali
do you suggest me change magnitude and position of source term?

[diamondx]

yes of course do it so you can pinpoint the problem....

[amir_14]

Originally Posted by diamondx

yes of course do it so you can pinpoint the problem....

tanx for your help dear Ali
I will try this