Properties of fluids

Properties of fluids:

In this article, we will learn about Properties of fluids

The important characteristics of Fluids are given below.

1. Density
2. Specific weight
3. Specific Volume.
4. Relative density
5. Viscosity
6. Compressibility
7. Surface tension
8. Capillarity
9. Cohesion
10. Adhesion
11. Pressure

1. Density or mass density or specific mass:

Density is the ratio of the mass of a fluid to its volume. We denote this by the letter p. In SI units, the unit of density is kg / m3. Mathematically,

Density p = Mass / Volume = m / V kg / m3

Mercury’s density is 13600kg / m. The density of water is 4 ° C at standard temperature and 1000 kg / m3 at standard atmospheric pressure.

2. Specific weight or weight density:

Specific weight is the ratio of the weight of the rus fluideor to its volume. Its value is the same for liquids, and its value for gases depends on gravitational acceleration, pressure and temperature. Let us denote it by the letter W. Its unit is N / m3 ‘or KN / m’. Mathematically,

Specific weight w = Weight / Volume = W / V = mg / V = pg N / m3

The specific weight of the water is 9810N / m3 or 9.81KN / m3 at standard temperature 4C° and standard atmospheric pressure. Specific Weight of Water

w = pg = 1000 kg / m ‘x 9.81m / sec2 = 9810 kg.m / sec / m3 As 1 kg.m / sec = 1N, Specific weight of water = 9810N / m3 = 9.81KN / m3

3. Specific volume:

Specific volume is the volume of a homogeneous fluid. If we write V, we denote the unit m3 / kg. Mathematically.

Specific volume = Volume / Mass = 1 / p m3 / kg

4. Relative density:

Relative density is the ratio of the density of a liquid to the density of a standard fluid. We take water to the fluid as the standard fluid and the air to the gases as the standard fluid. We denote this by the letter S. Mathematically,

Relative density s = density of a fluid/density of a standard fluid

In general, the density of a liquid = S x density of water = Sx 1000 kg / m3

5. Viscosity:

The viscosity of a liquid is the resistance force that it flows. It can also be referred to as coefficient viscosity or dynamic viscosity or absolute viscosity. We denote this by the letter A. Its unit is N.s / m3.

We sometimes use the term kinematic viscosity for our solar system. This is the ratio of absolute viscosity to density. These

We denote by the letter v (nu): Mathematically,

Kinematic viscosity v = Absolute viscosity / Density = u / P m2 / sec

The viscosity of a liquid is proportional to its temperature. This means that viscosity decreases as temperature rises and viscosity increases when temperatures decrease.

6. Compressibility:

Compressibility is the change in the volume of the fluid according to the pressure variation in the fluid. For a fluid, we call it the incompressible fluid because the volume of the pressure is too small.

7. Surface tension:

The surface tension is the tensile force acting on the surface of the fluid when it touches the liquid. We denote this by – Its unit is N / m.

Suppose three molecules A, B, and C are present in a liquid in a tank. The molecules A and B are equally attracted in all directions by the liquid molecules surrounding it. So they are balanced. But the molecules C is on the surface of the liquid. So that the downward force acting on it.

Thus, the downward force acting on all the molecules on the surface of a liquid. So that the layer on the surface of the fluid is very thin due to the pull force. We call this fluid surface tension.

Examples: 1. Rainwater appears to be a sphere when it falls to the ground. 2. Small objects like nail, needle, wood piece floating above the water.

8. Capillarity:

When a tube of small diameter is inserted into the fluid tank, the tube is found to be higher or lower than the level in the tank. When the level of fluid in the tube rises, we call it the capillary rise, and the fluid in the tube is called capillary depression. We denote this by cm or mm. Its value depends on the fluid’s specific weight, cohesion, adhesion, the surface tension of diameters.eu.

9. Cohesion and Adhesion:

The liquid consists of several molecules. Each molecule is attracted by all the molecules in its vicinity. This molecular attraction is called cohesion if it resides in the same fluid. Adhesion is the molecular attraction between different molecules of different materials. Example.

The gravitational force between liquid molecules and solid molecules. When the adhesion of the liquid and solid surface exceeds the cohesion in the liquid, the liquid will moisten the solid. For example, water dilutes the solid. When the cohesion in the liquid exceeds that of the solid and the adhesion in the liquid, the liquid does not wet the solid. For example, mercury does not wet the solids.

Engineerinsgtopic