Fluid Mechanics_Chapter_02_Units of Measurements

Fluid Mechanics

Chapter 02

Units of measurements

• Units of measurements

                    Before I go into depth to study hydraulics it is necessary to know the various units used for the measurement of various quantities in hydraulics. Please see the below table for measurement of hydraulics

Table

• Properties of fluids

1. Density - is known as specific mass or mass density. The density that is symbol of fluid is the mass of unit volume of the fluid.

Formula

The mass density and the specific weight are related as

Formula

When g is the acceleration due to the gravity of all particles possessed, the specific weight of water is taken as 1000 kg per cubic metre for 1 gram per cubic centimetre at 4 degree centigrade.

2. Specific weight

It is the weight per unit volume.Standard value of w of water is 1000 kg per metre cube in MKS unit or 9810 Newton per metre cube in SI unit are 9.81 kilo Newton per metre cube in SI unit.

Specific gravity 

It is defined as the ratio of the wait of fluid to the weight of an equal volume of water at specified standard temperature of 4 degree centigrade. The dimensionless ratio

Specific volume

Specific volume is the volume occupied by unit weight of the fluid. It is a reciprocal of specific weight it is measured in metre cube per kg.

Compressibility

Compressibility of a liquid is a measure of the change in the volume of the fluid when it is subjected to external force it is inversely proportional to the bulk modulus of elasticity of the fluid which is defined as

Formula

Where DP is the change in pressure dv is the change in volume And v its original volume.

Viscosity

It is the property of a liquid which resist  any deformation. In other words, liquids  withstand a slight amount of tension due to the molecular attraction between the particles which will cause an apparent shear resistance between two adjacent layers of liquid.

It is observed that thin liquids like water or alcohol slow much more easily dam thick liquids like ta heavy oil etc. Liquid itself possesses some property which controls the rate of flow of liquid within the working condition. A liquid which flows easily is called less viscous and that which flows slowly is called more viscous.

Read from the book modify some formula as per need