Lecture
9
Faculty of Engineering
Fluid Mechanics
Dr. Hasan
Hamouda
Fluid Kinematics
Fluid
kinematics
is
a
branch
of
Fluid
mechanics,
which
deals
with
the
study
of
velocity
and
acceleration
of
the
particles
of
fluids
in
motion
and
their
distribution
in
space
without
considering
any
force
or
energy
involved
.
Fluid Kinematics
•
Fluids in motion

Ideal fluids

Streamlines

Equation of continuity

Bernoulli’s equation

Venturi Meter
Ideal Fluids
•
The motion of real fluids is very complicated.
•
Using some simplifying assumptions to define
an ideal fluid allows a reasonable description
of much of the behavior of fluids.
•
An ideal fluid is
incompressible
and
•
its flow is:
laminar,
non

viscous &
irrotational.
Streamlines
A streamline is the path traced out by a tiny
element of the fluid (a fluid “particle”).
The velocity of the fluid particle is tangential
to the streamline.
Streamlines never cross.
A set of streamlines can define a tube of flow,
the borders of which the fluid does not cross
Fluid types
Uniform & non Uniform flow
Steady & Unsteady flow
Changing in space
Changing in time
Laminar & Turbulent flow
(Transition)
Rate of Flow (discharge)
Rate of Flow

Continuity Equation
Continuity Equation
In flowing liquids, the mass going
through a certain area equals the
mass going through any other area
Fluid incompressible, so volume
D
V
through
1
in time
D
t same as volume
through
2
, i.e.
D
V = A
1
v
1
D
t = A
2
v
2
D
t
A
1
v
1
= A
2
v
2
Q
1
= Q
2
The
volume flow ra
te
R = Av is
constant (units m
3
/s).
As fluid has constant density (it is
incompressible)
The
mass flow rate
R
= Av
is also constant
(units kg/s).
Mass flow rate
Continuity Equation
Example
1
Example
2
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