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-   -   Why does dtmax affect stability limits with fixed epsi? (http://www.cfd-online.com/Forums/flow-3d/71132-why-does-dtmax-affect-stability-limits-fixed-epsi.html)

gennady December 16, 2009 10:47

Why does dtmax affect stability limits with fixed epsi?
 
I use a fixed epsi and sometimes F3D applies a very small time step due to stability limits. I have found that a decrease of dtmax leads to increase of stability limits and time step. It sounds good because residuals are still kept below epsi and F3D runs faster. But this is like a magic.
Please could somebody give a hint why this happens?

Thank you.

MuxaB December 26, 2009 13:43

Quote:

Originally Posted by gennady (Post 240211)
I use a fixed epsi and sometimes F3D applies a very small time step due to stability limits. I have found that a decrease of dtmax leads to increase of stability limits and time step. It sounds good because residuals are still kept below epsi and F3D runs faster. But this is like a magic.
Please could somebody give a hint why this happens?

Thank you.

Gennady,

Did my email to you with response to this question last week make sense?

Michael


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