# Properties of Fluids

## Properties of Fluids

Fluids are the substances which begin to flow when an external force is applied to them. The liquids and gases together termed as fluids, in other words, we can say that the substances which can flow are termed as fluids. The mechanical properties of fluids can be categorized into two branches i.e. hydrodynamics and hydrostatics. Hydrodynamics deals with the study of fluids in motion whereas hydrostatic deals with the study of fluids at rest.

Since fluids are, like solids, also a form of matter, they have certain properties. The study of the properties of fluids in fluid mechanics helps us to utilize them for useful purposes.

Properties of Fluids: Though each fluid is different from others in terms of composition and specific qualities, there are some properties which every fluid share.

These properties can be broadly categorized under:

• Kinematic properties such as velocity and acceleration.
• Thermodynamic properties of fluidssuch as density, temperature, internal energy, pressure, specific volume and specific weight.
• Physical properties of fluidssuch as appearance, colour and odour.

Density: Density of a fluid is its mass per unit volume. It is the ratio between the two. Unit of Density of fluids is kg/m³.

$$Density(\rho )\,\,=\,\,\frac{Mass(m)}{Volume(V)}$$.

The density is dependent on a number of factors such as pressure, temperature and its chemical combination.

Temperature: The property of fluids that determines the state of hotness or coldness of it. Temperature is measured in either Kelvin, Celsius or Fahrenheit. Kelvin is the most common one that is used because of its independence from the properties of the substance.

Pressure: The pressure of a fluid is the force applied by it per unit area. The unit of pressure of fluids is N/m².

Specific Volume: In fluid mechanics, specific volume is the reciprocal of density. It can be expressed as the volume that a fluid occupies per unit mass. Specific volume is denoted by the letter ‘v’. Its unit is m³/ kg.

$$Specific\,\,Volume\,\,=\,\,\frac{Volume}{mass}$$.