Discussion Forum

Hi

there are many materials that are already set up for T dependency, you can look at these.
If you write your equation in the User defined conduction BC tab, then try:

(-1.27E-9*(T[1/K])^3+8.09E-6*(T[1/K])^2- 8.37E-3*(T[1/K])+22.72)[W/m/K]

Be sure the T is to be defined in Kelvin, or adapt the units

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Good luck
Ivar

Hi Ivar,

Thank you very much for your suggestion. It solved my problem.
Now in the next step I am trying to develop a two temperature model of heat transfer. I am not getting an idea how to implement this using COMSOL. I have attached a file with the equations to be used in 2T Model.
Do you have any suggestion as in How should I proceed?

Thanks in advance.

Best Regards,

Manoj

Hi

I'm not sure I fully follow,
do you mean a HT PDE solver on two domains (in connection or not) for which you solve the dependent variable T (bit as T is a field you have T(x,y,z,t) and for one domain and the other the same T has two different value ranges, one per domain, as these define different points (x,y,z) ?

Or are you talking about one domain onto which you want to solve two "T" dependent variables, in which case you should add 2x the HT physics with a T1 and T2 two different dependent variables, that you then might couple some way, or not on the domain or boundaries ?

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Good luck
Ivar

Hi Ivar,

Thank you very much for your reply.

Yes it is one domain, let us say we have a material with some dimension in 2D. When it is irradiated with femtosecond laser pulse, it gets heated. now in order to do transient study of heat transfer phenomenon I need to consider both electron (Te) and Lattice temperature (Tl) of the system.We are using a volumetric heat source and consider Beer Lambart's law for laser absorption in the material.
I am not getting an idea like how do I handle this electron and lattice temperature in COMSOL?
is it so simple that I should add twice the Heat transfer Physics with time dependent study and couple those 2 physics for the same system?

Thanks again for your help.

Best Regards
Manoj

Hi Ivar,

Thank you very much for your reply.

Yes it is one domain, let us say we have a material with some dimension in 2D. When it is irradiated with femtosecond laser pulse, it gets heated. now in order to do transient study of heat transfer phenomenon I need to consider both electron (Te) and Lattice temperature (Tl) of the system.We are using a volumetric heat source and consider Beer Lambart's law for laser absorption in the material.
I am not getting an idea like how do I handle this electron and lattice temperature in COMSOL?
is it so simple that I should add twice the Heat transfer Physics with time dependent study and couple those 2 physics for the same system?

Thanks again for your help.

Best Regards
Manoj

Hi

I would consider this yes, two HT, one for each species, but you need some good linking expressions since the physics of both must couple somehow, as its the same "material block"

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Good luck
Ivar

Hi,

Thank you very much again for your quick reply.
In order to coupe those two species I am using electron phonon coupling factor. I should look for a way to couple it.

Best Regards,

Manoj

Whetehr this model was successful? whether you were able to obtain lattice/electron temperature as a function of laser heating?