
[Sponsors] 
thermal conductivity > anisotropic material 

LinkBack  Thread Tools  Search this Thread  Display Modes 
July 15, 2010, 01:52 
thermal conductivity > anisotropic material

#1 
Member
Join Date: Nov 2009
Location: Germany
Posts: 96
Rep Power: 12 
Hello,
i have a thermal conduction problem. I need to modell a cylinder with different conductivity values in x,y and z direction. The cylinder is within a metal tube (isotropic material ) I think i can simply create 3 variables in transportproperties. Let's say lambdaX, lambdaY and lambdaZ. But after that i haven't a glue what to do next. (I'm pretty new to OpenFoam). Thanks in advance. Toni 

July 19, 2010, 09:12 

#2 
Senior Member
Ben K
Join Date: Feb 2010
Location: Ottawa, Canada
Posts: 140
Rep Power: 15 
You just need to make a volTensorField for your thermal conductivities. In your time=0 directory, create your conductivity field using something like:
Code:
FoamFile { version 2.0; format ascii; class volTensorField; object Ds; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 1 0 0 0 0]; internalField uniform (xx 0 0 0 yy 0 0 0 zz); boundaryField { ... } 

July 20, 2010, 05:26 

#3 
Member
Join Date: Nov 2009
Location: Germany
Posts: 96
Rep Power: 12 
Hi,
thanks for your reply. How will the solver recognize the new file? Don't i have to modify the solver for that? 

July 20, 2010, 08:19 

#4 
Senior Member
Ben K
Join Date: Feb 2010
Location: Ottawa, Canada
Posts: 140
Rep Power: 15 
You'll have to add the field by:
Code:
volTensorField lambda ( IOobject ( "lambda", runTime.timeName(), mesh, IOobject::MUST_READ, IOobject::AUTO_WRITE ), mesh ); Code:
dimensionedTensor lambda(transportProperties.lookup("lambda")); 

March 21, 2018, 14:42 

#5  
Member
Join Date: Oct 2017
Posts: 52
Rep Power: 4 
Quote:


March 21, 2018, 20:49 

#6 
Senior Member
Peter Baskovich
Join Date: Jul 2014
Posts: 126
Rep Power: 7 
Hi Val,
What solver are you using? Since it's cylindrical, do you want cartesian defined conductivities (x y z) or cylindrical coordinates (ρ,φ,z). I can help if you are using multiregion solvers such as cht. Benk's code goes in you solver source, which would then need to be recompiled, are you at that level? Regards Peter 

March 22, 2018, 00:41 

#7 
Senior Member
Uwe Pilz
Join Date: Feb 2017
Location: Leipzig, Germany
Posts: 590
Rep Power: 9 
If the temperature distribution outside the cylinder is of lesser interest, or if the conductivity there is much larger than in the cylinder, you may think about a coordinate transformation: Change the cross section of the cylinder for a circle to an ellipse according the proportion of conductivity and change its length too.
This gives you at least a forst idea of the solution.
__________________
Uwe Pilz  Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950) 

June 5, 2018, 06:32 

#8  
Senior Member

Quote:
Hi Peter, I am using cht to model heat transfer between fluid and solid. suppose I have a cylinder and fluid passing across the cylinder. Could you please help me to define anisotropic thermal conductivity. It would be great, if I don't need to recompile a solver. I am using Cartesian coordinate system. Along radial direction (x and y coordinate) thermal conductivity is same but it is different along axial direction. Moreover, in both direction (radial and axial), it is temperature dependent. Thank you Regards 

June 15, 2018, 00:06 

#9 
Senior Member
Peter Baskovich
Join Date: Jul 2014
Posts: 126
Rep Power: 7 
Hi Muhammad,
My example did not use temperature dependent capacity functions but that shouldn't be too hard to add. To implement a cylindrical coordinate system edit the thermophysicalProperties file of the domain and make it look like this: Code:
/** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 3.0.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; object thermophysicalProperties; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // thermoType { type heSolidThermo; mixture pureMixture; //transport constIso; transport constAnIso; //<this bit thermo hConst; equationOfState rhoConst; specie specie; energy sensibleEnthalpy; } coordinateSystem //< and this bit { type cartesian; // global coordinate system (redundant) origin (0.009 0.017861 0); coordinateRotation { type cylindrical; // local Cartesian coordinates //e1 (1 0 0); e3 (0 0 1); // axis of rotation } } mixture { specie { nMoles 1; molWeight 50; } transport { kappa (.1 10 10); //radial tangential longitudinal } thermodynamics { Hf 0; Cp 50; } equationOfState { rho 1000; } } // ************************************************************************* // Section 7.1.3, you will probably want janaf or polynomial. 

September 11, 2019, 16:06 

#10  
New Member
bharadwaz
Join Date: Nov 2018
Location: India
Posts: 13
Rep Power: 3 
Quote:
is it center of the cylinder Thank you 

September 27, 2019, 13:58 
New Issue in Anisotropic Conductivity

#11 
New Member
Join Date: Dec 2018
Posts: 2
Rep Power: 0 
Dear all,
I'm trying to verify the chtMultiRegionFoam (v1706) for the case of anisotropic conductivity (kappa). I'm comparing the results obtained with the following two configurations: 1. Isotropic mode, where I set the following: thermoType { type heSolidThermo; mixture pureMixture; transport constIso; thermo hConst; equationOfState rhoConst; specie specie; energy sensibleEnthalpy; } mixture { ... transport { kappa 170; } ... } 2. Anisotropic mode: thermoType { type heSolidThermo; mixture pureMixture; transport constAnIso; thermo hConst; equationOfState rhoConst; specie specie; energy sensibleEnthalpy; } coordinateSystem { type cartesian; origin (0 0 0); coordinateRotation { type axesRotation; e1 (1 0 0); e2 (0 1 0); } mixture { ... transport { kappa (170 170 170); } ... } For some reason, the results are different (the isotropic case is correct). Anyone here knows why the anisotropic case doesn't replicate the results? Do you see something that is wrongly set in thermophysical properties? Thank you in advance, Eugenio 

September 30, 2019, 03:07 

#12  
New Member
shach
Join Date: Apr 2019
Posts: 26
Rep Power: 3 
Hi,
just a hint, when you are using constAnIso solid, be sure at the boundary condition T you are using directionalSolidThermo at kappaMethod. Also add a aniAlpha. The names I am not very sure, you may google it. Maybe this is the reason. Quote:


September 30, 2019, 04:03 

#13  
New Member
Join Date: Dec 2018
Posts: 2
Rep Power: 0 
Quote:
I needed to define the boundary condition in internal walls (between solids) in the following way: nonIsotropicWall { ... kappaMethod directionalSolidThermo; alphaAni Anialpha; ... } 

September 30, 2019, 08:17 

#14 
New Member
shach
Join Date: Apr 2019
Posts: 26
Rep Power: 3 
Good to hear that!
However, I remember I had a problem about this directionalSolidThermo function. Though the result is correct, the wall heat flux calculated by wallHeatFlux function is not correct. I am not sure if its due to my setting or the function itself. So, be careful if you are using wallHeatFlux to calculate the heat flux. 

Thread Tools  Search this Thread 
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
mass flow in is not equal to mass flow out  saii  CFX  12  March 19, 2018 05:21 
Simulation of a single bubble with a VOFmethod  Suzzn  CFX  21  January 29, 2018 00:58 
Constant velocity of the material  Sas  CFX  15  July 13, 2010 08:56 
Anisotropic Thermal Conductivity  Saturn  CFX  4  January 30, 2007 12:34 
TwoPhase Buoyant Flow Issue  Miguel Baritto  CFX  4  August 31, 2006 12:02 