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whyingwang November 4, 2012 22:26

solving with Courant Number became larger and larger
 
Hello,
recently I use icoFoam to solv a channel flow.I am comfused because when it calculate ,I find the Courant Number become larger and large.
At first Courant Number mean: 1.40671e-05 max: 0.0146915
But after 12 steps it become Courant Number mean: 1.57099e86 max: 2.66405e91
And then it stops.
I want to know why it happend,how can I circumvent it.

P.S.
in controlDict,I set runTimeModifiable true,see below:
runTimeModifiable true;

adjustTimeStep yes;

maxCo 1;

maxDeltaT 7.5e-7;

treima November 5, 2012 03:06

Hi,

did you try a smaller Courant-number, like 0.1 for example?


regards
treima

whyingwang November 5, 2012 10:10

Quote:

Originally Posted by treima (Post 390240)
Hi,

did you try a smaller Courant-number, like 0.1 for example?


regards
treima

thanks,
you means when I set the delta T,I make the Courant-number equals 0.1.
or I set the maxCo 0.1 directly.

treima November 6, 2012 03:06

I mean the setting of the maxCo directly to 0.1 (or another small value).

Have you tried this?

whyingwang November 7, 2012 19:43

Quote:

Originally Posted by treima (Post 390467)
I mean the setting of the maxCo directly to 0.1 (or another small value).

Have you tried this?

Thanks,
Yes, I tied.But I fixed this problem at another point.
At last I found that the pre-compiled icoFoam does not support adjustable timestep control.I need to re-compile this icoFoam.
After adding
#include "readTimeControls.H"
and
#include "setDeltaT.H"
after
#include "initContinuityErrs.H" and #include "setDeltaT.H"
respectively.
Now I can control the Courant Number below any number.


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