The state postulate for incompressible substances, particularly in fluid mechanics, is often simplified by treating liquids like water as incompressible, despite their compressibility. To define the thermodynamic equilibrium state of liquid water, two independent intensive properties are necessary, as illustrated in its phase diagram. For solids, the state is defined similarly, requiring two intensive variables, with Hooke's law incorporating compressibility in three dimensions. The discussion highlights the lack of emphasis on the state postulate for incompressible substances in textbooks, despite its relevance in thermodynamics.
PREREQUISITESStudents and professionals in mechanical engineering, fluid mechanics, and thermodynamics, particularly those interested in the properties of incompressible substances and their applications in real-world scenarios.
Please identify what you consider an incompressible system.Signature said:State postulate for a simple compressible system is completely specified by two independent intensive properties.
But what about state postulate for a incompressible system.
Why it is not so important?
just considering only liquids specifically waterChestermiller said:Please identify what you consider an incompressible system.
Liquid water is compressible, so it still takes specification of two intensive properties to define its thermodynamic equilibrium state. See the phase diagram for water.Signature said:just considering only liquids specifically water
Chestermiller said:Liquid water is compressible, so it still takes specification of two intensive properties to define its thermodynamic equilibrium state. See the phase diagram for water.
It's certainly mentioned in thermodynamics books. Look up Poynting Correction.Signature said:Let it be, but, in most cases especially fluid mechanics we treat water as an incompressible liquid. Anyway if there is an incompressible substance, what are the basic properties which are required to completely specify its state. Why no textbooks did mention about the state postulate of incompressible substances?
I'm sure you are aware that there is no such thing as a completely incompressible liquid.Signature said:But Poynting correction is for real gases. But I want to know about incompressible substance.
Ok sir. Then what about the state postulate for solidsChestermiller said:It's certainly mentioned in thermodynamics books. Look up Poynting Correction.
Chet
How can we define the state of solidsSignature said:Ok sir. Then what about the state postulate for solids