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-   -   UDS Flux Boundary Condition (http://www.cfd-online.com/Forums/fluent/117826-uds-flux-boundary-condition.html)

shashank312 May 15, 2013 21:25

UDS Flux Boundary Condition
 
The gradient of the UDS is zero at the boundary. How to implement this using DEFINE_PROFILE? Would C_UDSI_G work?

blackmask May 15, 2013 21:33

Do I misunderstand your question or did you overlook the menu items? You can set the boundary condition for UDS from the b.c. menu.

shashank312 May 15, 2013 21:34

I overlooked the menu. I can specify the flux on the GUI. My bad.

shashank312 May 15, 2013 21:39

On a different note, can I do the following?

Set C_UDSI_M1(c,t,0) = C_UDMI(c,t,0);
where C_UDMI(c,t,0) is a product of some constants, temperature and volume fraction gradient.

Solve for C_UDSI(c,t,0) using the DEFINE_UDS_UNSTEADY and DEFINE_DIFFUSIVITY.

Then do this: C_UDMI(c,t,1) = C_UDSI(c,t,0)*C_T(c,t);

Is yes, please let me know how.

blackmask May 15, 2013 22:26

I am not quite sure what you want to do.
Could not you solve the equation for (temperature X volume fraction gradient) instead of the volume fraction gradient?
Correct me if I am wrong. When you use DEFINE_UDS_UNSTEADY, the C_UDSI_M1 is not used. Why do you have to assign a value to it?

shashank312 May 15, 2013 22:33

Okay, this is what I want to do. Maybe a diverted a little bit.

I find the interfacial mass source term (interfacial means where the vof of one of the phase is neither 1, nor zero and the vof gradient is not zero) and then I store that term in UDMI(c,t,0).

I need to solve the unsteady diffusion equation for the above mass source term, so that I get a "diffused" or "smeared" mass source term which I can store in a new location and use to specify my energy source term.

I hope you get what I am trying to do here. Please help me out!

blackmask May 15, 2013 22:49

Then I do not find any problem in your last post.

shashank312 May 15, 2013 22:51

Okay. Do you know how to implement it though on FLUENT in correct order, with the correct usage of macros?


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