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How to give temperature dependent gas properties?

Posted 21 set 2010, 08:15 GMT-4 Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD) Version 5.2 4 Replies

Atilla Savas
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I would like to solve a multiphysics problem involving navier stokes, heat equation and magnetic field (actually a TIG welding problem ). I have some graphics involving the viscosity, density of the Argon gas changing with the temperature. How can I implement these graphic values into COMSOL . Should I change these graphic values into third or fourth degree equations or is there a way to implement them directly. I use COMSOL 3.5a
4 Replies Last Post 6 giu 2017, 11:24 GMT-4
Markus Berger
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Posted: 1 decade ago 21 set 2010, 08:43 GMT-4
Hi Attila,

best prepare a text file containing rows of data (T and eta(T) for viscosity) and then select Options->Functions...
There you define a new function using "Interpolate form File". Read in your viscosity data and use the function
as the gas property in the domain settings. The density does not need to be read from a file, because COMSOL
can calculate it from the ideal gas law (check box in domain settings).

Markus
Hi Attila, best prepare a text file containing rows of data (T and eta(T) for viscosity) and then select Options->Functions... There you define a new function using "Interpolate form File". Read in your viscosity data and use the function as the gas property in the domain settings. The density does not need to be read from a file, because COMSOL can calculate it from the ideal gas law (check box in domain settings). Markus
Atilla Savas
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Posted: 1 decade ago 21 set 2010, 09:07 GMT-4
Thank you Markus,

Your recomendation solved my problem.
Thank you Markus, Your recomendation solved my problem.
Atilla Savas
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Posted: 9 years ago 23 mag 2016, 08:12 GMT-4
I am experiencing another problem when I use Comsol 5.2. Comsol does not understand eta(T) as temperature dependent viscosity. Should I use another syntax rule. I am defining an interpolation function giving the eta values at different temperatures, but I cannot get COMSOL understand it. How should I solve this problem?
I am experiencing another problem when I use Comsol 5.2. Comsol does not understand eta(T) as temperature dependent viscosity. Should I use another syntax rule. I am defining an interpolation function giving the eta values at different temperatures, but I cannot get COMSOL understand it. How should I solve this problem?
Andrea Roberto Calore
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Posted: 7 years ago 6 giu 2017, 11:24 GMT-4

I am experiencing another problem when I use Comsol 5.2. Comsol does not understand eta(T) as temperature dependent viscosity. Should I use another syntax rule. I am defining an interpolation function giving the eta values at different temperatures, but I cannot get COMSOL understand it. How should I solve this problem?


Hi. Have you solved your problem?
[QUOTE] I am experiencing another problem when I use Comsol 5.2. Comsol does not understand eta(T) as temperature dependent viscosity. Should I use another syntax rule. I am defining an interpolation function giving the eta values at different temperatures, but I cannot get COMSOL understand it. How should I solve this problem? [/QUOTE] Hi. Have you solved your problem?

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