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update the pyhsicaltimestep during a steady-state-run

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Old   April 3, 2009, 08:18
Default update the pyhsicaltimestep during a steady-state-run
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Matthias Voß
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hey,

i am doing a mesh study and i am facing really slow convergence within the highest/finest mesh . So i could increase my timestep.
According to the other runs on the coarser meshes i know that i can increase my phsyical timestep bit by bit.
So i linked the physicaltimestep with an expression,like:

"Timestep*Factor(CITERN)"
to increase it depending on my iterationnumber.


Tried it with the AutoTimeScale--> No problem. Updating the value means updating the factor means new timescale.

But with PhysicalTimeScale the solver doesn't update the value for the timescale, so my function isn't working.

Any idea how i can force the solver to update the value for the physical timescale automatically? Maybe smth. like an ExpertOption.

Best regards,
neewbie
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Old   April 3, 2009, 08:27
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Martijn
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I think this has to be done in Fortran. Probably in a similar way as described in "Junction Box Example 3: Timestep Control" in the help function of CFX-11.
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Old   April 6, 2009, 00:09
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Em... It confused me.
For steady-state simulation, why does time step need to be defined in CFX?
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Old   April 6, 2009, 01:48
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Glenn Horrocks
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Hi:

neewbie - your CEL is almost right. The variable name is "citern" in lower case. It is case sensitive. Look in the documentation for the exact naming of variables.

Martijn - No need for fortran. CEL should be fine.

Jasmine - CFX uses a timestep to advance the simulation, even in a steady state simulation. Read the documentation on this or do a search on past posts on this issue.

Glenn Horrocks
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Old   April 6, 2009, 03:08
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Matthias Voß
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hi,


thanks for the response.
I used the capital letters only for entering the post... in the expression i wrote "citern".
Btw. the expression did well with the AutoTimeScale but not with the Physical... which is not loose because why should the solver update a value which is ought to be fixed over the run.
Any further ideas?

neewbie
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