# solving with Courant Number became larger and larger

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 November 4, 2012, 22:26 solving with Courant Number became larger and larger #1 New Member   Wang Han Join Date: May 2012 Location: Shanghai China Posts: 21 Rep Power: 6 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;

 November 5, 2012, 03:06 #2 Member   Join Date: Mar 2012 Location: Munich, Germany Posts: 67 Rep Power: 6 Hi, did you try a smaller Courant-number, like 0.1 for example? regards treima

November 5, 2012, 10:10
#3
New Member

Wang Han
Join Date: May 2012
Location: Shanghai China
Posts: 21
Rep Power: 6
Quote:
 Originally Posted by treima 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.

 November 6, 2012, 03:06 #4 Member   Join Date: Mar 2012 Location: Munich, Germany Posts: 67 Rep Power: 6 I mean the setting of the maxCo directly to 0.1 (or another small value). Have you tried this?

November 7, 2012, 19:43
#5
New Member

Wang Han
Join Date: May 2012
Location: Shanghai China
Posts: 21
Rep Power: 6
Quote:
 Originally Posted by treima 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.
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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