anisotropic thermal conductivity

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gsw_001
Posts: 3
Joined: 17 Mar 2010, 07:25

anisotropic thermal conductivity

Post by gsw_001 »

HI

I have been unsuccessfully trying to input orthotropic 2D thermal conductivities into the heat equation model.

I thought this was supported in Elmer based on the discussion of Model 1 - Heat Equation where it says that "For solids, conduction may be anisotropic and the conductivity a tensor"

I followed the Tutorial 10 approach for an anisotropic Youngs modulus on page 50 to no avail. A result from one of my many attempts is given below:

Excerpt from the SIF file:

Material 1
Name = "solid"

Density = 1550
Heat Capacity = 1450
Heat Conductivity
size 2 2
real 0.1 0.6
0.6 0.1
end
End



Elmer tells me:

Error:: Model Input:
Error:: Model Input: Unknown specifier: [end]
Error:: Model Input: In Section: [material 1]
Error:: Model Input: For propert name: [0.6 0.1]


Is it possible to have solve a solids heat conduction problem with anisotropic thermal conductivity using Elmer?
If so, can you please explain how to do it?

thanks

gsw
eraikkon
Posts: 2
Joined: 03 May 2010, 12:34

Re: anisotropic thermal conductivity

Post by eraikkon »

I would also be very interested in the answer.
raback
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Re: anisotropic thermal conductivity

Post by raback »

Hi

I think that the expression for heat conductivity is missing a line feed between the two rows. In fact you can have all the entries on the same row, the size decleration alone decleares the size, not the layout of the numbers. I would try with the following:

Code: Select all

Heat Conductivity(2,2) = Real 0.1 0.6 \
                              0.6 0.1

or as the variabletype is known a priori simply

Code: Select all

Heat Conductivity(2,2) = 0.1 0.6 0.6 0.1

-Peter
tacojoi
Posts: 20
Joined: 16 Mar 2011, 14:22
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Re: anisotropic thermal conductivity

Post by tacojoi »

Hi,
According to the above view, I think

(a) If I have a 2D model, kx = 1.0 & ky = 0.0, so
Heat conductivity(2,2) = Real 1.0 0.0 0.0 0.0

(b) Same as (a), kx = 0.0 & ky = 1.0, so
Heat conductivity(2,2) = Real 0.0 0.0 0.0 1.0

(c) If I have a 3D model, kx = 0, ky = 0 & kz=1.0, so
Heat conductitvity(3,3) = Real 0.0 0.0 0.0 0.0 0.0 1.0

Is that correct?
Please help me to confirm.

BR,
Taco.
raback
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Re: anisotropic thermal conductivity

Post by raback »

Yep, except in 3D you need 9 components, not six. -Peter
tacojoi
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Re: anisotropic thermal conductivity

Post by tacojoi »

Hi, Peter,

Thanks a lot.

Taco
annier
Posts: 1168
Joined: 27 Aug 2013, 13:51
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Re: anisotropic thermal conductivity

Post by annier »

Hi,
Seeing the much relevance of anisotropic heat conduction in solids, I am trying to refresh this discussion started 7 years ago.
2D Model
kx = 0, ky = 1.0, so

Code: Select all

Heat conductitvity(2,2) = Real 0.0 0.0  0.0 1.0
3D Model
kx =1. 0, ky = 5.0 & kz=1.50, so

Code: Select all

Heat conductitvity(3,3) = Real 1.0 0.0 0.0 0.0 5.0 0.0 0.0 0.0 1.50
Yours Sincerely,
Anil Kunwar
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
annier
Posts: 1168
Joined: 27 Aug 2013, 13:51
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Re: anisotropic thermal conductivity

Post by annier »

Hi All,
Is it possible to vary the anisotropic material property with coordinates in Elmer?
Relevant threads:
1. viewtopic.php?f=3&t=3139&start=0&hilit=tensor+variable
2. viewtopic.php?f=7&t=2267&start=0&hilit=user+subroutine

Variation of a tensor with Coordinate
1.viewtopic.php?f=3&t=3802&start=0&hilit=tensor+matc
2. viewtopic.php?f=3&t=110 (length limit of matc)


Yours Sincerely,
Anil Kunwar
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
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