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June 23, 2009, 13:48 
Temperature Gradient at Wall

#1 
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Sven Winkler
Join Date: May 2009
Posts: 70
Rep Power: 9 
I am simulating a laminar channel flow with heated walls. To calculate y nusselt number I first want to calculate the temperature gradient at the wall. Unfortunately I couldnt find some function similar to "WallGradU" which is able to calculate the wall temperature gradient, like "WallGradU" does it for the velocity gradient. Has anyone an idea how I could get the temperature gradient out of OpenFOAM? Can the "WallGradU" function be edited to get the temperature gradient?


June 23, 2009, 22:18 

#2 
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Jitao Liu
Join Date: Mar 2009
Location: Jinan , China
Posts: 64
Rep Power: 9 
Hi sven,
I am interested in this problem too. I am new to OpenFOAM. I want to simulate the filling process of nonnewtonian fluids into a heated cavity.The energy equation was added to the interFoam solver to calculate the temperature field. At the heated wall: 1) The temperature of nonnewtonian fluid is assumed equal to the wall's (in my case，the thermal conductivity of the wall is much larger than that of the nonnewtonian fluid ). 2) A coupled solver such as chtMultiRegionFoam can be created to solve this problem. Combination of heatConductionFoam and interHeatFoam (interFoam with energy equation) for conjugate heat transfer between a solid region and fluid region. I am working on the second part. If there is any development, please let me know. Best regards, Jitao Last edited by awacs; July 20, 2009 at 04:42. 

June 24, 2009, 04:27 

#3  
Senior Member

Hi Sven,
Make a copy of wallGradU, replace U with T, volVectorField with volScalarField and dimensionedVector with dimensionedScalar. It should work! Regards, Jose Santos Quote:


June 24, 2009, 12:16 

#4 
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Sven Schweikert
Join Date: Jun 2009
Posts: 38
Rep Power: 9 
Hi Santos  thanks for your reply.
I have the same intention like sven and tried your advise. Sadly I received some errors while creating the new wallGradT: Line 80  error: Expected primaryexpressions before '(' token Line 83  error: 'scalar' is not a class of namespace PHP Code:
About some additional help I would be really helpful. Thanks a lot & regards svens 

June 24, 2009, 12:20 

#5 
Senior Member

Replace scalar::zero with 0 and all should be well.
Regards, Jose Santos 

June 24, 2009, 15:23 

#6 
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Sven Schweikert
Join Date: Jun 2009
Posts: 38
Rep Power: 9 
It works! Perfect  thanks so much.


July 23, 2010, 05:04 

#7 
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n/a
Join Date: Sep 2009
Posts: 198
Rep Power: 9 
Question: I am able to compute the mean temperature gradient at a specified patch of my choosing. The is essentially 3D, hence the I have a 2D plane wall temperature gradient. Can anyone give me any feedback or advice as to how I can average the temperature gradient along a wall direction, so that I end with an output that comprises two columns such as: x dTmean/dn
x1 ***** x2 ***** Thanks. Deji 

November 1, 2010, 18:25 

#8  
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Join Date: Nov 2009
Posts: 48
Rep Power: 8 
Hello Jitao,
I would like to know if you were successful with your implementation. I am interested in such a coupled solver ( combination of heatConductionFoam and interHeatFoam ). I would be so grateful if you can help me. Thanks, Mehran Quote:


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