My question may be pretty basic, but I feel it is important to ask this as I've gone through several texts and none offer me the clarity I seek.
The question is: What is a fluid? What is flow? If we say that a fluid is something that flows, the next right question to ask would be what flow is. To my surprise and disappointment, there is no clear distinction between various definitions, which I present in the form of questions -
- Is a fluid simply something that can flow?
- Is a fluid, an object that can be continuously deformed, as a result of shear forces? (fluids can't sustain tangential stress)
- What is flow? Does it refer to the motion of fluid elements relative to one another, or does it refer to the motion of the fluid as a whole with respect to the container it is contained in? or, is it just the continuous sliding/deformation of fluid layers, which texts refer to as flow?
So, what properties really define a fluid? (Something that brings up a clear distinction between fluids and non-fluids)
A detailed explanation would be great. Thanks a lot.