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-   -   Thermal radiation with solids rotating (http://www.cfd-online.com/Forums/cfx/25466-thermal-radiation-solids-rotating.html)

luis March 16, 2008 22:04

Thermal radiation with solids rotating
 
Hi everyone,

I am working with a steady state simulation in CFX 11, with CHT, solid domain rotating (Beta Feature), radiation. I have some issues over here.

1. Does anybody knows which should be the absorption coefficient "correct" values for steel, for example? I found in some literature that value to be 0.35 cm^-1. I have also the refractive index for some materials with its imaginary part (Extinction coefficient) and i found those values to be in order of 2e+9 to 7e+09 m^-1. Which value should i use? i am using 0 m^-1 but i don't trust in these results, because i want to do some material comparison to check the temperature profile.

2. When i turn on the option "Include motion advection" for rotating solids, the temperature just diverge. Is it right to ignore that feature?

3. I am also modeling airflow, with massflow at outlet. Unfortunately the solver is interpreting that outlet as part wall, part outlet, and it is asking me to switch to opening b.c. . Additionaly the velocity vectors doesn't appear to be correct. I've tried with scale mass flows option, shift pressure and constant. No one of them gave me trustable results. I have to increase the temperature of some walls near outlet and then the solver is working well, but that situation is not reality. Any ideas?

4. i got an error message in CFX, which is not allowing me to work in DesignXplorer, altough the solver is able to write the results file:

----------------------------------- -----------------------------------

Details of error:- Error detected by routine PEEKCA CDANAM = CVAR CRESLT = NONE

Current Directory : FLOW/SOLUTION/TSTEP4/CLOOP1/ZN3/BELG12/IP

ERROR #001100279 has ocurred in subroutine ErrAction Message: Stopped in routine MEMERR ------------------------------------ ------------------------------------

5. Does anybody know which is the "right" turbulence model for airflow with thermal radiation? i used k-e and the results varies a lot respect with SST and k-w.

Thanks so much for any help,



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