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;
}

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

Dose anyone help me? Thanks....

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

Oh, well, thanks all the same。。。:)

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...

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

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