[pitch]

hello ;
i need help , i am simulating a rotating airfoil and i wrote a udf for the motion by define_zone_motion so i define psi (azimuth angle ) psi =omega*(time) and omega is the rotational speed.
but i want to activate the source term only in 90° to 120° azimuthal position

appreciate any help please
thanks

[vinerm]

Your description is little unclear. Is there issue with zone motion UDF or with source UDF?

[pitch]

Thank you
For the source term how to active with azimth position because to use in define_source the same angle defined in zone_motion it sows error that undeclared variable

[vinerm]

So, all you need is to know the azimuthal position within DEFINE_SOURCE. If the rotational displacement or speed is user parameter then you can do the same calculation in DEFINE_SOURCE and apply the source if the position is within the required bounds.

[pitch]

dear vinerm
i am using this
DEFINE_ZONE_MOTION(blade,omega,axis,origin,velocit y,time,dtime)
{

psi=omegac*(time);
return;

}
DEFINE_SOURCE(Source1, c, t, dS, eqn)
{
real Source;
real time = RP_Get_Real("flow-time");
real psi=omegac*(time);

if (psi>= 90*M_PI/180 && psi <= 100*M_PI/180 )
{
Source=C_UDMI(c,t,F); ****i saved C_UDMI(c,t,F)*****
dS[eqn]=0;
}
else
{
Source=0.0;
dS[eqn]=0;
}
return Sourcex;

}

[vinerm]

Hi

If this is the complete UDF then I have doubts that it works. Your SOURCE UDF is alright. It should work perfectly, except for two issues. What is omegac? It is not defined anywhere. Furthermore, what is F, the last argument of UDM? The last argument should correspond to the number of the UDM. If you have only one UDM in your case, then it should be 0 and not F. Of course, you can call it F provided you declare int F = 0; in your code.

ZONE_MOTION is supposed to provide velocities and not position. If omega is fixed or changing with time, you do not need this UDF. For fixed omega, just provide the number in the cell zone conditions. If it is changing with time, then you can use this UDF or profile. But in that case, UDF requires modification. psi is not defined anywhere nor is omegac.

As far as time is concerned, it is not a property of any macro. This is available to all macros. You can directly use CURRENT_TIME instead of using RP macro. CURRENT_TIME is a C based variable defined in Fluent and is equal to the current simulation time.

[pitch]

Originally Posted by vinerm

Hi

If this is the complete UDF then I have doubts that it works. Your SOURCE UDF is alright. It should work perfectly, except for two issues. What is omegac? It is not defined anywhere. Furthermore, what is F, the last argument of UDM? The last argument should correspond to the number of the UDM. If you have only one UDM in your case, then it should be 0 and not F. Of course, you can call it F provided you declare int F = 0; in your code.

ZONE_MOTION is supposed to provide velocities and not position. If omega is fixed or changing with time, you do not need this UDF. For fixed omega, just provide the number in the cell zone conditions. If it is changing with time, then you can use this UDF or profile. But in that case, UDF requires modification. psi is not defined anywhere nor is omegac.

As far as time is concerned, it is not a property of any macro. This is available to all macros. You can directly use CURRENT_TIME instead of using RP macro. CURRENT_TIME is a C based variable defined in Fluent and is equal to the current simulation time.

Can you give me your skype or email to contact you please

[pitch]

Psi is defined

[Svetlana]

omegac is not defined in the code; can you please add it?

[pitch]

Originally Posted by Светлана

omegac is not defined in the code; can you please add it?

Thank you
Its defined befor define zone motion its just not shown
Real omegac =500rpm

[Svetlana]

Can you please post the complete code?

[vinerm]

From any of your posts, it is not clear what the issue is. Did you try the code? In my view, if you make the changes recommended by Svetlana and me, it would work alright. Let us know if you face any issue and also post the issue that you face.

[pitch]

Originally Posted by vinerm

From any of your posts, it is not clear what the issue is. Did you try the code? In my view, if you make the changes recommended by Svetlana and me, it would work alright. Let us know if you face any issue and also post the issue that you face.

i change theif so it is as fonction of time not omegac

but stil the Sourcex=0 so it's not changing with time

[vinerm]

Are you able to run a simulation with this code? Fluent would give error as soon as you compile it or interpret it. It should be C_UDMI(c, t, 1), assuming you have at least 2 UDMs in your simulation. If there is only one UDM, then it should be C_UDMI(c, t, 0). You cannot use F as an argument. If you wish to multiply UDM value with F, it has to be C_UDMI(c,t,0) * F or C_UDMI(c,t,1) * F. And C_UDMI should have a value that is different from 0.

[pitch]

[QUOTE=vinerm;758737]Are you able to run a simulation with this code? Fluent would give error as soon as you compile it or interpret it. It should be C_UDMI(c, t, 1), assuming you have at least 2 UDMs in your simulation. If there is only one UDM, then it should be C_UDMI(c, t, 0). You cannot use F as an argument. If you wish to multiply UDM value with F, it has to be C_UDMI(c,t,0) * F or C_UDMI(c,t,1) * F. And C_UDMI should have a value that is different from 0.[/QUOTE

DEFINE_SOURCE(X_Source1, c, t, dS, eqn)
{
real Sourcex;
real time= CURRENT_TIME;

if (0.0 <= CURRENT_TIME < 0.02 )
{
Sourcex=C_UDMI(c,t,Fx1);

dS[eqn]=0;
}
else if (0.02<= CURRENT_TIME < 0.03 )
{
Sourcex=0.0;
dS[eqn]=0;
}
return Sourcex;

}
please for all variables are defined in the code just too lange to show so the problem is in time
and after i compile it no error

[vinerm]

Alright, I am assuming that the indices that you use for UDMs are defined, either as integers or enum. And they have to be, otherwise your code would not have worked. There are also a few commands that are not of any use, such as, extraction of Zone ID. First thing you can check is the time of your case. Use the following command in TUI to see whether the time is between 0 and 0.02 or not.

(rpgetvar 'flow-time)

Also, at least for the debugging, use a smaller time-step, such as, 0.002. If the time is within the bounds where source should have some value other than 0 then do the following

1. Write a profile file as follows, using any text editor.

((sourcex transient 3 0)
(time
0
0.02
0.03
)
(src
900.0
1000.0
0.0
))

2. Read this into Fluent and hook in place of Source UDF.
3. Run the case for one time-step and see if you observe the effects of the source.

[pitch]

IT SHOWS > (rpgetvar 'flow-time)
invalid command [(rpgetvar]
**and i included the brackets *

[vinerm]

Did you do a copy and paste from the post? Then it will give this error. Yes, you have to use parentheses but you need to type the command.

[pitch]

Originally Posted by vinerm

Did you do a copy and paste from the post? Then it will give this error. Yes, you have to use parentheses but you need to type the command.

so i change it to
DEFINE_SOURCE(X_Source1, c, t, dS, eqn)
{
real Sourcex;
real time= CURRENT_TIME;

if (0.0 <= CURRENT_TIME < 0.001 )
{
Sourcex=C_UDMI(c,t,Fx1);
dS[eqn]=0;
}
else if (0.001 <= CURRENT_TIME < 0.003 )
{
Sourcex=0.0;
dS[eqn]=0;
}
return Sourcex;
}
i get this
> (rpgetvar 'flow-time)
0.001

[vinerm]

What I meant is that you keep your code as it but use a smaller time-step in Run Simulation panel. As far as using profile is concerned, do not use the UDF. Use only the profile and check if it works.