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I am confused on material properties
Posted 26 août 2014, 13:58 UTC−4 1 Reply
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I just can't see any rhyme or reason to the material properties for various materials.
For example, I am trying to see how my model changes if I change the gas I use from helium, to regular air, to CO2. Particularly I need the speed of sound for those materials. Air has this:
cs(T[1/K])[m/s]
Which I take to be some function. I can copy that over to other materials, but I get an "unkown function: cs" error.
Secondly, I am getting an error for oxygen. Apparently I need to provide COMSOL with the Young's modulus and Poisson ratio for oxygen. I can't find that anywhere online, probably because those two values don't apply to gases really.
Back to the speed of sound thing for a second: since I'm doing an acoustic frequency sweep, I take it I can use a constant for the speed of sound at my given temperature? The static pressure remains constant as does the temperature, so I shouldn't need anything besides a constant, right?
For example, I am trying to see how my model changes if I change the gas I use from helium, to regular air, to CO2. Particularly I need the speed of sound for those materials. Air has this:
cs(T[1/K])[m/s]
Which I take to be some function. I can copy that over to other materials, but I get an "unkown function: cs" error.
Secondly, I am getting an error for oxygen. Apparently I need to provide COMSOL with the Young's modulus and Poisson ratio for oxygen. I can't find that anywhere online, probably because those two values don't apply to gases really.
Back to the speed of sound thing for a second: since I'm doing an acoustic frequency sweep, I take it I can use a constant for the speed of sound at my given temperature? The static pressure remains constant as does the temperature, so I shouldn't need anything besides a constant, right?
1 Reply Last Post 29 août 2014, 10:32 UTC−4
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Posted:
1 decade ago
If you unfold the 'air' node (click the small triangle in front of it) you will see that it has subnodes with further subnodes. Somewhere in this tree you will find the definition of the 'cs' function. You have to copy this also to the other material before it will work.
When does comsol ask for the Young's modulus and Poisson ratio?
When does comsol ask for the Young's modulus and Poisson ratio?