what property I can use for Air in simulation?

Hi,

For my model, I needed to put air as a part. When I do run static simulation, what material properties of young's modulus, possion ratio, thermal conductivity....I can use?

when I try to suppress the air part, somehow the simulation won't go further....as I need to have the air part to make cavity inside of my model.

So, it seems that I need either to put reasonable matrial properties....or some how to let simulation ignore the air part...though it needed to make air cavity....can anyone give me advice? for first option, I think that air don't have possion ratio...or any dummy property I can use?

Thanks,

Cheol

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