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-   -   Adjusting UDM to UDS (http://www.cfd-online.com/Forums/fluent-udf/118031-adjusting-udm-uds.html)

mvee May 20, 2013 00:50

Adjusting UDM to UDS
 
Hi

I have define adjusted UDM to UDS and for this UDS I am not solving any transport equation, hence default BC i.e flux zero and solution UDS equation in off mode.

Now in the contours of UDM and UDS, there is mismatch at on the boundaries. Because I have used, C_UDMI() = C_UDSI(). This assigns the cell centroid values only. Now in order to assign face centroid values I followed below mentioned ways but it did not work.

(1) define_profile condition on boundaries.
(2) similar to cell centroid adjustment, face centroid adjustment

If any one have tried on this issue. According to you which option should work.

Thanks in advance for your reply
Mvee

mvee May 21, 2013 00:29

any response?

blackmask May 21, 2013 22:48

Have you tried to loop all the face threads and cell threads?
The UDM is not associated with certain type of boundaries.

mvee May 22, 2013 04:27

I opted the second the way i.e adjusted the face centroid values also. This is only possible by Lookup_Thread on defined face thread.

blackmask May 22, 2013 05:18

I speculate that the difference appeared in the contour is due to different interpolation schemes for UDM and UDS. Is the mismatch most apparent at the edge of your b.c.? For two-faced b.c. like interface, the UDM is not defined but I think UDS would be defined there.

mvee May 22, 2013 07:51

I got the solution.
As I told you that for C_UDMI to C_UDSI , the cell centroid values are transfered; while it is considering the BC values on the face which is not the actual physics. Values of the algebraic expression that is stored in memory should transferred everywhere which in turn overwrite the BC. To achieve this in addition to cell centroid values, face centroid values are also incorporated through additional face loop.

blackmask May 22, 2013 08:37

So what is the difference between you final solution and your first post in this thread?

mvee May 23, 2013 02:02

Both the ways are correct. First option you can utilize on the face for which transport equation is required to be solved while second option can be utilized when there is no need of solution of scalar transport equation. Second option requires proper looping macros where I was doing mistake.


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