When is a fluid incompressible?
Definition of compressibility
Next:Equations of the frictionless compressible Up:Compressible currents Previous:Second law of thermodynamics
All real fabrics are more or less compressible. When they are subjected to compressive stress, their density changes. This is particularly the case with gases, less so with liquids and hardly with solids. The amount by which a medium can be compressed at a given pressure is called Compressibility designated.
Let us consider a small volume element, Figure 6.1. Mathematically, compressibility is defined as the relative change in volume with a change in pressure dp .
Figure 6.1: Definition of compressibility
Eq. (6.52) is not precise enough. If we change the volume of the volume element, we also need to know what kind of process we are using to achieve this. If the temperature is kept constant, we speak of a isotherms Process and receive
and with the entropy fixed we get that isentropic Compressibility
The role of compressibility in determining the properties of a flow can be described as follows. If we in Eq. Inserting (6.52) gives that
I.e. when the pressure changes dp the fluid experiences a corresponding change in density . From the last equation it follows
For interpretation we consider the flow around a profile. If the fluid is a liquid, the compressibility is very small, then the density change as a result of a change in pressure dp very little from one point to another. This means that we can assume with sufficient accuracy that the density is constant and that the liquid is therefore incompressible. When a gas flows around it, the compressibility is on the other hand very large and already small dp cause not negligible changes in density, so that a gas flow i. general compressible is. Form an exception to this Low velocity currents. In this case the pressure change is dp small, so even with large only a very small change in density takes place.
We will see later that the Mach number, i.e. the ratio between flow velocity and speed of sound,
is particularly suitable to describe the importance of compressibility.
Next:Equations of the frictionless compressible Up:Compressible currents Previous:Second law of thermodynamicsroot
Sun Dec 15 23:00:07 CET 1996
- How has a hearing aid changed your life?
- How can Africa solve its educational problem
- Can I brush my German sheepdog teeth
- Is blood cancer curable with stem cells?
- How can I start communicating?
- Are SD cards faster than USB sticks
- The dog that was sent into space died
- How effective is the Coursera certification in itself
- Who named the 50 states of America
- What is the english name of halwa
- Artificial sweeteners make you fat
- Which leather is good for a car
- How is neurolinguistic programming different from hypnosis?
- Does someone use Exporters India
- Which receipts should I keep
- Has anyone ever stolen the White House?
- How is trauma-induced dissociative amnesia treated
- Why do people attack bus drivers
- What are junk files in the phone
- What is a young tree
- How do you approach a federal judge
- What is the best cheap tea
- What is preventing you from becoming homeless
- What are the best restaurants in Michigan
- How can I pump down an air conditioner
- How many atoms does sugar contain?
- Haha is LOL
- What is great potential
- How does arginine make your muscles fuller
- Why don't my hashtags register on Instagram
- Why is horizontal agriculture obsolete?
- Have you already told someone that you are gay?