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Problem with scalarTransportFoam illistrated using pitzDaily tutorial 

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March 21, 2010, 13:55 
Problem with scalarTransportFoam illistrated using pitzDaily tutorial

#1 
New Member
Michael Lawson
Join Date: Apr 2009
Location: NREL  Boulder, CO
Posts: 11
Rep Power: 9 
Hi All,
I have been using scalarTransportFoam to simulate chemical transport in a very complex geometry. While the value of my scalar should remain between 0 and 1, I see values as high as 2.5. To troubleshoot this problem I went to the scalarTransportFoam tutorial pitzDaily. When the diffusivity (DT) is set to 0.01 in transportProperities the maximum value of the scalar should remain between 0 and 1, but goes as high as ~1.007  this is not a big problem. However, if the diffusivity (DT) is changed to 1e6 and the tutorial is rerun, the scalar value goes to ~1.43, with the maximum value along the wall. This level of error is unacceptable. Additionally, I tried changing the fvSchemes from the default tutorial settings to: div(phi,T) Gauss upwind; laplacian(DT,T) Gauss linear uncorrected; This did not help the problem. Does anyone have any suggestion on settings for the fvSchemes dictionary that would fix this problem? Thanks in advance, Mike 

March 24, 2010, 12:10 

#2 
New Member
Michael Lawson
Join Date: Apr 2009
Location: NREL  Boulder, CO
Posts: 11
Rep Power: 9 
Hi again,
The problem appears to be with "createPhi.H". If you run the simpleFoam tutorial pitzDaily and copy U and phi at the final timestep over to the scalarTransportFoam pitzDaily tutorial, then rerun scalarTransportFoam the solution remails bounded between 0 and 1. If you then move phi to phi.hold and rerun scalarTransportFoam, the solution is no longer bounded between 0 and 1. Additionally, the phi that is created by scalarTransportFoam is significantly different from the phi.hold which was written by the simpleFoam solver. In many cells, the phi value differs by 10% or more. I'm at a loss for what the problem could be here... Anyone have any ideas? Mike 

January 18, 2011, 14:39 

#3  
Senior Member
Daniel P. Combest
Join Date: Mar 2009
Location: St. Louis, USA
Posts: 585
Rep Power: 20 
Quote:
http://www.cfdonline.com/Forums/ope...lations2.html I hope this helps. Dan 

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