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Thermal conductivity

Posted Jul 4, 2012, 7:50 a.m. EDT Heat Transfer & Phase Change, Parameters, Variables, & Functions Version 4.2a 3 Replies

Philip Jönsson
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Hi
I have a geometry mith two different materials and i want to know the thermal conductivity of the whole geometry. I know how to use COMSOL to evaluate the thermal conduktivity but i want to know what COMSOL is doing when it evaluate it.

If anyone could tell me this I would be the happiest man alive.

Thanks in advance.
3 Replies Last Post Dec 18, 2013, 12:13 p.m. EST
Chraibi Omar
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Posted: 1 decade ago Jul 10, 2012, 4:59 a.m. EDT
Hi Philip,

I have the same problem. I have a non homogen geometry with two materials and I would like figure the equivalent thermal conductivity.

Normally, to calculate the equivalent thermal conductivity we should use the "heat flux". But I don't know how can I use this condition.

Once you have the total flux then you can calculate the conductivity using :

phi=-lambda*S*grad T

Thank you.




Hi Philip, I have the same problem. I have a non homogen geometry with two materials and I would like figure the equivalent thermal conductivity. Normally, to calculate the equivalent thermal conductivity we should use the "heat flux". But I don't know how can I use this condition. Once you have the total flux then you can calculate the conductivity using : phi=-lambda*S*grad T Thank you.
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Jul 10, 2012, 11:16 a.m. EDT
Hi Philip,

Thermal conductivity is a material property not a property of a whole geometry. I guess you mean the equivalent or effective thermal conductivity had your geometry been made of a uniform material. COMSOL solves the heat equation in each part of the geometry using its own thermal properties. You can then extract the effective properties via post-processing.

Note that for many multi-material systems the effective thermal conductivity will be different in different directions, even though all the constituents have isotropic values.

Nagi Elabbasi
Veryst Engineering
Hi Philip, Thermal conductivity is a material property not a property of a whole geometry. I guess you mean the equivalent or effective thermal conductivity had your geometry been made of a uniform material. COMSOL solves the heat equation in each part of the geometry using its own thermal properties. You can then extract the effective properties via post-processing. Note that for many multi-material systems the effective thermal conductivity will be different in different directions, even though all the constituents have isotropic values. Nagi Elabbasi Veryst Engineering
Marziye Mirbagheri
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Posted: 1 decade ago Dec 18, 2013, 12:13 p.m. EST
Hello,

I am very new in COMSOL and trying to calculate effective thermal conductivity in 2D but I am not sure how to do this. I know I need to find heat flux but I am not sure if I am doing the process correct. I'd appreciate any help and explain to solve this problem.

Thanks and Regards,
Marziye.
Hello, I am very new in COMSOL and trying to calculate effective thermal conductivity in 2D but I am not sure how to do this. I know I need to find heat flux but I am not sure if I am doing the process correct. I'd appreciate any help and explain to solve this problem. Thanks and Regards, Marziye.

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