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HETVAL subroutine: FLUX(2)

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eklee

Civil/Environmental
Aug 3, 2015
8
How should FLUX(2) in the HETVAL subroutine be defined? The Abaqus user subroutine reference manual did not seem to help.

Thanks,
Emily
 
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When I write the DFLUX Fortran subroutine, I specify the flux value to FLUX(1) and the time rate of change of FLUX(1) to FLUX(2).
It just helps the solver along, I don't think it is required for Abaqus/Standard, in fact I think I usually just write FLUX(2)=0.
However, if you are using Abaqus Explicit then it may be much more important for convergence rates.

Haven't checked HETVAL vs. DFLUX, but if they are anything alike this analogy should apply.

What I would do to test this theory is try FLUX(2)=0 and FLUX(2)=100 in your analysis and check the difference.

Just off the top of my head, anyway.
 
Thank you very much! That does help. I had FLUX(2)=1.0 and it seemed to work just fine. I was just a little worried having it equal a constant if it is supposed to be a rate of change.

Do you know how to determine if I am using Abaqus standard or Explicit?
 
Also, I just tried running with FLUX(2)=0 and it worked fine. However, with FLUX(2)=100 it exited with an error.

Any thoughts?
 
Maybe 100 was a bad example, and a solution could not converge in the required increment, because it starts with an inaccurate starting point, and residuals are too high.
I was trying to say that a simple test like trying 1, and 0 may answer your question.

When your solver licenses are checked out, are you using standard or explicit?
For example, when you run your job through DOS just type in "abaqus licensing lmstat -f" while your job is running and see what is checked out.

Another way is to check your step definition in the input file,
i.e. something like "*Dynamic, Explicit, adiabatic" may be the line you are looking for.
 
And sorry, I wasnt thinking clearly earlier and must offer a correction. Flux (2) should be derivative w.r.t. temperature. Only, if your flux does not have temperature dependence it should be zero.
 
Okay, thanks! Currently I have:
FLUX(1)=(cp*density*(tref-REAL(TEMP(1))))/DTIME/10
FLUX(2)=0.0

It seems to be working just fine. Do you think FLUX(2) is okay being equal to zero in my case?
 
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