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UDF boundary condition (heat flux), in corrugated area (adjustment factor needed))

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Old   June 10, 2021, 00:57
Default UDF boundary condition (heat flux), in corrugated area (adjustment factor needed))
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Jose Martin
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Hi all,

First of all I would like to thank you for having a look my problem and helping me to solve it!

I have prepared a small document to describe my problem (please find the attached file), and I would like you to help me with the UDF definition, because the solution I have found does not work (there is a small deviation, you can see it in the last pic of the attached file).

Here the description, and all details in the attached file:

"I need to extrapolate the projected received heat flux for a corrugated area. Thus, I need to include in the UDF a factor in order to take it into account. The problem is for a corrugated tube, which receives a constant value of radiative heat flux, and if I corrugate the tube, the flux in this specific area will be lower (because the face cell projected area devided by the face cell area is smaller than 1, and this factor is what I need to include in the UDF), then to extrapolate this dimensional factor I would like to define a factor which is the projected area in Z coordinate (where the heat flux is constant) devided by the face area"

The UDF definition (just for theis factor) is a follow :

F_AREA(A,f,t); /* Function projected area */

AA=pow(A[0]*A[0]+A[1]*A[1],0.5)/NV_MAG(A); /* Factor to adjust the received heat flux in the face cell*/

QMAX=AA*Q; /* Adjusted heat flux*/

Hope you can help me, I guess it is not a very complicated issue, but I do not find the solution.

Many thanks in advance

Solution: When defining variables it needs to be "double" instead of "real", even I am runing the simulations in double precision..... I thought it was a tolerance problem....

Last edited by JMM_UC3M; June 10, 2021 at 07:08.
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