# alpha1 is unbounded

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October 17, 2012, 04:48
alpha1 is unbounded
#1
Senior Member

Gerhard Holzinger
Join Date: Feb 2012
Location: Austria
Posts: 195
Rep Power: 17
Hello,

I am trying to simulate a bubble column with twoPhaseEulerFoam. When running my case alpha1 reaches values that should not be possible.

Code:
```Courant Number mean: 0.00734422 max: 0.637501
Max Ur Courant Number = 0.453228
Time = 0.675

MULES: Solving for alpha1
Dispersed phase volume fraction = 0.000455625  Min(alpha1) = -0.00187942  Max(alpha1) = 1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.000455625  Min(alpha1) = -0.540265  Max(alpha1) = 1```
There is some checker-boarding next to the inlet. Does anyone have some tips how to eliminate that.
Attached Images
 checkerBoardingAlpha1.jpg (12.4 KB, 27 views)
Attached Files
 bubbleColumn.tar.gz (5.7 KB, 6 views)

 October 17, 2012, 05:25 #2 Senior Member     Anton Kidess Join Date: May 2009 Location: Delft, Netherlands Posts: 1,163 Rep Power: 20 Try using a much smaller time step. __________________ *On twitter @akidTwit *Spend as much time formulating your questions as you expect people to spend on their answer. *Join the OpenFOAM stackexchange Q&A site: http://area51.stackexchange.com/prop...oHPxcPqde7HtA2

 Tags twophaseeulerfoam

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