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-   -   need help about UDS & VOF (http://www.cfd-online.com/Forums/fluent/74772-need-help-about-uds-vof.html)

mengyue1 April 8, 2010 05:41

need help about UDS & VOF
 
hi guys, i am simulating a system, the fluid involved in this system is water,water vapor and air, because of gradient of vapor mass fraction, there exists phase change.
i don't plan to use the species model available in FLUENT, in my model, i define there phases, which are water,vapor(phase-3) and air, and also, i introduce a UDS to model the diffusion of vapor in the air, the scalar is vapor mass fraction, is that right?
I define the uds for phase-3, and i think i need define vapor/air diffusivity for this uds. but now i am confused with it. in the material pannel, each material has a "UDS Diffusivity", and which one i should introduce my udf for diffusivity? when i introduce udf to vapor, there are some error tips in FLUENT:

Error:
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: ()
but when i define the same udf for other materials(air and water), there are not errors.
Can someone tell me the reason... i think my udf should define for vapor, not the other materials...

Regards!

PS::confused:the code is:

DEFINE_DIFFUSIVITY(diffusivity, cell, third, i)
{
Thread *mix_th, *sec_th;
real diff;
real v;
mix_th = THREAD_SUPER_THREAD(third);
sec_th = THREAD_SUB_THREAD(mix_th, 1);

if ((C_VOF(cell, sec_th)==1))
diff = 0.0;

else
diff = 3.02761*pow(10.0,-5.0)*C_MU_EFF(cell, mix_th);
return diff;
}




mengyue1 April 8, 2010 08:48

Dose anyone help me? thanks...and where is sega?

mengyue1 April 9, 2010 00:09

Dose anyone help me? Thanks....

sega April 9, 2010 06:39

Quote:

Originally Posted by mengyue1 (Post 253766)
Dose anyone help me? thanks...and where is sega?

sega is here! :)
But I think I'm not use here ...

mengyue1 April 13, 2010 21:44

Oh, well, thanks all the same。。。:)
Quote:

Originally Posted by sega (Post 253914)
sega is here! :)
But I think I'm not use here ...


DaddySpeleo April 12, 2012 09:59

I solved such problem by this way:

1. Make UDM containing the data gotten via C_VOF.
Simle cycle C_UDMI(...)=C_VOF(...)
2. Remove C_VOF(...) from DEFINE_DIFFUSIVITY
3. Use data from UDM in DEFINE_DIFFUSIVITY.

It seems to me - this error appears in some cases when macros C_VOF try to work. For example in solid area.
Best regards...

Kanarya February 7, 2014 10:51

hi,
did you manage to solve the problem...I have the same problem as you.
thanks for your help in advance!

DaddySpeleo February 7, 2014 18:40

I didn't try to do smth more exept described above method - this method works.
May be Fluent 15 is better?
Best regards!


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