Fluid Mechanics PPT important topics of mechanical engineering introduction to fluid mechanics and important definitions

1. Fluid Mechanics
Fluid mechanics is that branch of science, which deals with
the behavior of the liquid/ gases at rest as well as in motion.
Stages of Fluid Mechanics:
• Static Fluid- The study of fluid at rest.
•Kinematics of fluid- The study of fluid in motion and
pressure force are not considered.
• Kinetics/ Dynamics of fluid- The study of fluid in motion
but pressure force is considered.

2. Properties of Fluid:-
1. Density/ Mass density- Mass per unit volume is
called density.
Denoted by ‘ρ’ (rho) = M/V
M= Mass of fluid
V= Volume of fluid
Unit of mass= kg
Unit of volume= m3
So that Unit of density= kg/ m3 ,
Density of water= 1000 kg/ m3

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4. 2. Specific weight/ Weight density- It is the ratio of weight of
fluid to its volume.
Denoted by ‘W’= Weight of fluid/ Volume of fluid
Unit of weight density= N/ m3
Since, Weight= M*g
So that W = M*g/ V & (M/V= ρ= Density of water 1000 kg/
m3 )
So that weight density of water= 1000*g N/m3=1000*9.81
N/m3

5. 3. Specific volume- It is a inverse property of density.
i.e. Specific volume = Volume of fluid/ Mass of fluid = V/M=
1/ρ
4. Specific gravity- It is the ratio of the weight density of fluid to
the weight density of standard fluid.
i.e. Specific gravity=
Weight density of fluid/ Weight density of water
Water is a standard fluid. Weight density of water = 1000*9.81
N/ m3