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Old   June 30, 2016, 07:43
Question Question about anisotropic thermal conductivity
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Alex Szwaykowski
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Hi all,
I just started using STAR-CCM+ 9.02 as part of an internship and I've run into a problem that seems a bit over my head. I need to model the anisotropic thermal conductivity of a solid object and the issue I'm running into is that the thermal conductivity needs to be anisotropic and temperature dependent.

I was able to model temperature dependent thermal conductivity as a 'Polynomial in (T)' for isotropic thermal conductivity, but when I switch to anisotropic thermal conductivity (Continua> Physics> Models> Solid> Al> Material Properties> Thermal Conductivity), that option is no longer available. Instead, I have to go down through "Regions> Body> Physics Values> Anisotropic Thermal Conductivity> Principal Tensor" in order to describe the thermal conductivity in the XX, YY, and ZZ directions. Unfortunately, my only options for describing thermal conductivity values in these cases are to use a constant, a table, a field function, or a user code. It's a little strange that the option for 'Polynomial in T' exists for Thermal Conductivity, but not for Anisotropic Thermal Conductivity. Is there a reason for this, or am I just misunderstanding something?

Can anyone help me figure this out? I'm trying to learn how to use a field function or user code to do this and as someone who has never coded in C, C++, or Fortran, it's a bit overwhelming for me.
Thanks!
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Old   June 30, 2016, 08:34
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Hi,
You could use the "polynomial in T" and put it in form of a field function as you suggested; you should have the coefficients and exponants of your polynomial and the field function would have to be defined for the interval of temperatures you consider:
[T1 - T2] : a*T^b +c*T^d etc..
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Old   June 30, 2016, 09:26
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Thanks for the response,
Just to clarify, this would mean that I would define a unique field function for each direction (XX, YY, and ZZ) which would be defined by a polynomial involving the primitive field function "Temperature"; is this correct?
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