DEFINE_SOURCE - Problem

Hgyn · May 12, 2011, 06:45

Hello,
I'm trying to write a UDF for an laminar duct flow that effects the fluid like there is a semi-high wall in the middle. This is what i have:

#include "udf.h"

DEFINE_SOURCE(xmom,cell,thread,dS,eqn)
{
real source, CON = 10000.0;
face_t f;
Domain *domain;
domain = Get_Domain(1);

int zone_ID = 12;
Thread *rand = Lookup_Thread(domain,zone_ID);

begin_f_loop(f, rand)
{
source=-CON*C_U(cell,thread);
/* dS[eqn]=-CON; */
}
end_f_loop(f, rand)
return source;
}

Zone 12 is a wall which is adjusted on interior.
But the UDF is not working the way it should.
What's my fault.

Thanks

Amir · May 12, 2011, 16:41

Hi,
your UDF has some logical errors.
you loop over faces of your thread and then include source to the whole domain!!!
you have to separate a zone near the plate and include source to that.

Hgyn · May 13, 2011, 10:21

Thanks for your reply, I understand what you mean, so I implement a if-else-condition, but what can I use as condition, or how can I realise that the flow is just influenced at that position?

Amir · May 13, 2011, 10:35

As I said before, you have permission to add source terms to cells, so separate a zone near your area and then hook the UDF over separated zone in boundary condition panel.

Hgyn · May 13, 2011, 10:56

Got it, thanks a lot

May 12, 2011, 06:45	DEFINE_SOURCE - Problem	#1
Hgyn New Member Join Date: May 2011 Posts: 7 Rep Power: 15	Hello, I'm trying to write a UDF for an laminar duct flow that effects the fluid like there is a semi-high wall in the middle. This is what i have: #include "udf.h" DEFINE_SOURCE(xmom,cell,thread,dS,eqn) { real source, CON = 10000.0; face_t f; Domain domain; domain = Get_Domain(1); int zone_ID = 12; Thread rand = Lookup_Thread(domain,zone_ID); begin_f_loop(f, rand) { source=-CONC_U(cell,thread); / dS[eqn]=-CON; */ } end_f_loop(f, rand) return source; } Zone 12 is a wall which is adjusted on interior. But the UDF is not working the way it should. What's my fault. Thanks

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May 12, 2011, 16:41		#2
Amir Senior Member Amir Join Date: May 2009 Location: Montreal, QC Posts: 735 Blog Entries: 1 Rep Power: 23	Hi, your UDF has some logical errors. you loop over faces of your thread and then include source to the whole domain!!! you have to separate a zone near the plate and include source to that.

May 13, 2011, 10:21		#3
Hgyn New Member Join Date: May 2011 Posts: 7 Rep Power: 15	Thanks for your reply, I understand what you mean, so I implement a if-else-condition, but what can I use as condition, or how can I realise that the flow is just influenced at that position?

May 13, 2011, 10:35		#4
Amir Senior Member Amir Join Date: May 2009 Location: Montreal, QC Posts: 735 Blog Entries: 1 Rep Power: 23	As I said before, you have permission to add source terms to cells, so separate a zone near your area and then hook the UDF over separated zone in boundary condition panel.

May 13, 2011, 10:56		#5
Hgyn New Member Join Date: May 2011 Posts: 7 Rep Power: 15	Got it, thanks a lot