6. Hydrostatics: that studies the mechanics of fluids at absolute and
relative rest.
Kinematics: deals with translation, rotation and
deformation of fluid without considering the force and
energy causing such a motion
.
Dynamics: that prescribes the relation between velocities and
acceleration and the forces which are exerted by or upon the
moving fluids.
Fluid machanics
7. Properties of Fluids
Density is the mass of the fluid per unit volume
Density ()
= Density of fluid, kg/m3
M = Mass of fluid, kg
V = Unit volume, m3
= M
V
8. The specific weight is the weight of the fluid per unit
volume
= Specific weight, N/m3
W = Weight of fluid, N (W=mg)
V = Unit volume, m3
= W
V
The specific weight of water at 40C = 9.81 kN/m3
Specific Weight/Unit Weight ()
9. The specific gravity is the ratio of the density or
specific weight of the fluid to the density or specific
weight of water, at a temperature of 4oC
Specific Gravity/Relative Gravity (S)
S =
w
=
w
Dimensionless
10. Viscosity
It is the property of the fluid by virue of
which it offers resistance to shear or angular
deformation.
Mollases,tar, glycerine are highly viscous fluids.
Water,air,petrol have very small viscosity and are called
thin fluids.
11. Newton’s Law of Viscosity
= (du/dy)
Where, du/dy =velocity gradient
= coefficient of viscosity.
It’s states that the shear stress( ) on a fliud
element layer is directly proportional to the rate of shear
strian.
12. Classifiction of fluid
The fluid may be classified into the five types:-
1) Ideal fluid
2) Real fluid
3) Newtonian fluid
4) Non – newtonian fluid
5) Ideal plastic fluid