Does a phase transition occur also for an ideal fluid (from ideal gas to ideal uncompressible liquid)? Or ideal fluids can be modelled only as ideal gas or uncompressible liquid at all, without the possibility for a phase change?

I hope the question is well posed, thanks


1 Answer 1


Ideal gas and ideal fluid are not the same. Ideal fluid has molecular interaction that is even throughout different entities, and has no viscocity, and no compression.

Yes, ideal fluid is modeled so that it will go through phase change, but you would have to consider the gas from ideal fluid as a pseudo- real gas, since it has molecular interaction.

An ideal gas has no volume, has no interaction, will not go through any sort of phase change.

Hope this helps.

  • $\begingroup$ For sure any answer is helpful! So, correct if I'm wrong, if I assume that water vapour is an ideal gas, it will be always in the gas phase and hence the saturation dome will not exist. In the same way if I assume water as an (ideal) incompressible liquid? $\endgroup$
    – user29550
    Commented Aug 8, 2016 at 16:51
  • $\begingroup$ Yes. If you assumed water vapor as an ideal gas, no saturation dome would exist. Ideal incompressible liquids will have vapor pressure, and will saturate in a finite container given that there is sufficient amount of liquid. $\endgroup$
    – Caprica
    Commented Aug 8, 2016 at 21:45

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