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-   -   UDF - define_init & restart problem (http://www.cfd-online.com/Forums/fluent/110090-udf-define_init-restart-problem.html)

argeus December 3, 2012 17:27

UDF - define_init & restart problem
 
Dear friends,
There is one thing I cant figure out. I interpreted my UDF which was made as follows:
Define_init function. Is to examine the geometry parameters, to simplify it, it returns the total volume (c_tot variable) of the cells.
Define_source (whatever define macro), uses this value, such as x/c_tot. Everything works fine, until I end the calculation, write a .dat file and restart the calculation without initialization. Seems to be (and Im pretty sure), that Fluent does not store the c_tot value, in general any value, obtained from define_init once the calculation is over and then restarted. I really dont want to use a define_adjust (it will uselessly slow down my calculation), or define_on_demand (want to keep it to be performed automatically). Is there any way to store that value for the next usage?
Thank you in advance.
j.

argeus December 4, 2012 12:19

Hi again,
so it seems to be that I moved on a bit.
I found out that use of C_UDMI could be suitable for this kind of problem, anyway there is still an issue I cant pass through.
To explain it more closely:

Code:

DEFINE_INIT (init, domain)
{
  real ...
  thread_loop_c(t, domain);
      {
      begin_c_loop(c, tc)
        if (sth)
        {
        C_UDMI(c, tc, 0)+=C_VOLUME(c, tc);
        }
      end_c_loop(c, tc)
      }
}

and then

DEFINE_SOURCE(energy, c, thread, dS, eqn)
{
  real ...
  var1=var2/C_UDMI(c, tc, 0)
  source=var3;
  dS[eqn]=var4;
  return source;
}

Please have a look on that. Problem is, that C_UDMI is returning zero value (as an output from ini function), and I dont have a clue why.
Maybe I just dont understand how C_UDMI is working.
The second question is - Will be the C_UDMI value stored after I re-interpret my UDF, or restart the calculation from a .dat file? (Will be this value written into a .dat file?).
For now, Im using on demand macro, but it is not so pretty as I would like to.. :)
Thank you in advance.
Regards


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