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Comsol asking for Ratio of Specific Heats for solid.

Posted 1 févr. 2017, 08:48 UTC−5 Heat Transfer & Phase Change, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5.2 4 Replies

Anthony Lethuillier
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Hello,

I am trying to build a simple model that finds the temperature as a function of time.


The model is part gas / part solid I therefore used the Heat Trasnfer in Fluids physics and I defined the gas and solid parts.

When assigning material properties I use the materials defined in the database but it asks me to fill in the Ratio of Specific Heats for all materials (solid and gases).

According to en.wikipedia.org/wiki/Heat_capacity_ratio this is possible for gases but not for solids.

Am i doing something wrong or is it my understanding of the physics that are wrong ?

Thanks in advance for any help,

I've attached the model I'm working on.

4 Replies Last Post 12 mars 2017, 07:29 UTC−4
townbiscuit
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Posted: 8 years ago 3 févr. 2017, 10:57 UTC−5
Hey Anthony,

I`m still getting used with Comsol, but from my experience, this can happen if you define your physics wrong and you set up a study intended for a gas to a solid.. which could explain why Comsol is asking for the ratio of specific heats. Someone more experienced should confirm this though.
Hey Anthony, I`m still getting used with Comsol, but from my experience, this can happen if you define your physics wrong and you set up a study intended for a gas to a solid.. which could explain why Comsol is asking for the ratio of specific heats. Someone more experienced should confirm this though.
Lay Sotheary
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Posted: 8 years ago 11 mars 2017, 02:53 UTC−5
Hi
Did you find this solution? I also met this problem. If you found this solution, please you kindly let me know.

Thank you,
Theary
Hi Did you find this solution? I also met this problem. If you found this solution, please you kindly let me know. Thank you, Theary
Lasse Murtomäki
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Posted: 8 years ago 11 mars 2017, 05:37 UTC−5
For solids the ratio is 1.

For gases: Cp - Cv = R

Hence: Cv/Cp = 1 - R/Cp

Ideal gas law applies surprisingly well even at elevated temperatures and pressures.

Lasse
For solids the ratio is 1. For gases: Cp - Cv = R Hence: Cv/Cp = 1 - R/Cp Ideal gas law applies surprisingly well even at elevated temperatures and pressures. Lasse
Lay Sotheary
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Posted: 8 years ago 12 mars 2017, 07:29 UTC−4
Thank you, Lasse Murtomäki for your replying.
Thank you, Lasse Murtomäki for your replying.

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