The discussion revolves around the compressibility of fluids, specifically exploring the attributes that differentiate compressible fluids from incompressible ones. Participants examine the compressibility of various fluids, including liquids and gases, and consider practical implications in different contexts such as hydraulics and aerodynamics.
Participants generally agree that all fluids have some degree of compressibility, but there is no consensus on the implications of this compressibility in various applications. Multiple competing views exist regarding the significance of compressibility in different contexts.
Participants highlight that the compressibility of fluids can vary significantly based on practical applications and conditions, such as pressure and the presence of air. The discussion does not resolve the complexities surrounding the definitions and implications of compressibility in different scenarios.
This discussion may be of interest to those studying fluid dynamics, engineering applications involving hydraulics, and anyone exploring the properties of fluids in various scientific contexts.
No. Air is compressible.thetexan said:Are all fluids incompresible?
The word fluid includes liquids and gases. All fluids have some level of compressibility. The term incompressibity is an ideal limit of small, but finite, compressibility, and is often an excellent approximation.thetexan said:Are all fluids incompresible? If not, what is the attribute that allows any compressible fluid to do so while others, such as hydraulic fluid to not?
tex
Surethetexan said:So I should have used the work liquids. So, all liquids have "some" compressibility? Even hydraulic oil?
tex
Look up tables showing the property called 'bulk modulus' for various liquids. It's the inverse of compressibility. While in mechanical applications higher bulk modulus means you're losing less power on compressing the liquid, it's not always worth the effort of going for exotic substances (I don't think anybody is using mercury in their hydraulics, despite its superior bulk modulus).thetexan said:So I should have used the work liquids. So, all liquids have "some" compressibility? Even hydraulic oil?
tex
Can you please give a specific reaction example where the fluid dynamics are affected in a liquid phase system?DrDu said:This is also a question of what you are interested in. When you are talking about calculating the aerodynamics of a boat, the assumption of water to be incompressible is certainly excellent. If you are doing chemical reactions in an autoclave at 100 kbar, it might turn out to be rather poor.
I think the OP was referring specifically to fluid dynamic considerations.DrDu said:Not the fluid dynamics but the chemical reaction.
I had this article in mind (sorry, German only):
http://onlinelibrary.wiley.com/doi/10.1002/ciuz.19890230205/full
May be, I just wanted to indicate that the notion of whether a substance is compressible or not may be different between a naval engineer and a guy simulating nuclear bombs.Chestermiller said:I think the OP was referring specifically to fluid dynamic considerations.