This document defines and describes different types of fluid flows. It discusses ideal and real fluids, Newtonian and non-Newtonian fluids, laminar and turbulent flow, steady and unsteady flow, uniform and non-uniform flow, compressible and incompressible flow, rotational and irrotational flow, and viscous and non-viscous flow. Key fluid properties like viscosity, density, and compressibility are covered. Examples are provided to illustrate different fluid types and flows.

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2. Topic:
Quasi Steady and Unsteady flow
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3. What are FLUIDS
 a substance that has no fixed shape
and yields easily to external pressure;
a gas or (especially) a liquid
 Particles can move past each other
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4. Types of Fluid:
 Ideal Fluid
 Real Fluid
 Newtonian fluids
 Non- Newtonian fluids
 Ideal plastic fluids
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5. Ideal Fluids:
 A fluid ;
a) Is incompressible
b) Have zero viscosity
c) An imaginary fluid
d) No surface tension
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6. Real Fluid:
 A fluid
a) Have viscosity
b) Compressible
c) Have surface tension
d) For example; water
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7. Newtonian fluid
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8. Non-Newtonian fluid:
 The real fluid, in which the shear stress is
not directly proportional to the rate of
shear strain is know as non Newtonian
fluids.
 For example:
ketchup, custard, toothpaste, starch,
blood, and shampoo are non Newtonian
fluids.
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9. Ideal Plastic fluid:
 A fluid in which the shear stress is
more than the yield value and the
shear stress is directly proportional to
the rate of shear strain that is it should
follow Newton's law of viscosity.
 It behaves as a rigid body at low
stresses but flows as a viscous fluid at
high stress .
 Eg : tooth paste can be considered as
ideal plastic fluid
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11. MOTION OF FLUID PARTICLES
 The molecule of liquid and gas have
freedom to move.
 The motion of fluid depend upon the
fluid and shape of the passage
through which the fluid particles
moves.
 A fluid consist of an innumerable
number of particles,
 Whenever a fluid is in motion, these
particles move along certain lines 11

12. One dimensional flow
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The flow parameter
such as velocity is a
function of time and
one space co-ordinate
only.
U=f(x)
v=0
w=0

13. Two dimensional flow
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The velocity is a
function of time and two
rectangular space co-
ordinates.
U=f(x,y) v=f(x,y)
w=0

14. Three dimensional flow
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The velocity is a
function of time and
three mutually
perpendicular
directions.
U=f(x,y,z)
v=f(x,y,z)
w=f(x,y,z)

15. What is Reynold number
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 The ratio of inertia force to viscous
force is said to be the reynold number
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16. Reynolds number
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17. Small velocities:
Line of dye intact, movement in prallel layers.
High velocities:
Rapid diffusion of dye mixing. .
Critical velocities:
Line of dye begin to break up,transition
between laminar and turbulent.
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18. Types of fluid flow:
 Steady & Unsteady Flows.
 Uniform & Non-uniform Flows.
 Laminar & Turbulent Flows.
Compressible & Incompressible Flows.
Rotational & Irrotational Flows.
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19. Steady & Unsteady Flow:
 The steady flow In which the fluid
Characteristics like velocity, pressure,
density at a Point do not change with
respect to time.
The unsteady flow in which the fluid
characteristics velocity , pressure or
density at a point changes with respect to
time.
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21. Uniform & Non-uniform Flow:
The uniform flow is defined as the type
of fluid in which the flow parameters like,
pressure , velocity and density etc, at a
given time do not change with respect to
space.
The non-uniform flow is defines as the
type of fluid in which the flow parameters
like pressure , velocity, density etc, at a
given time change with respect to space.
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22. Laminar Flow:
The laminar flow in which the fluid
particles move along well
defined paths or
stream line.
 when a fluid flows in
parallel
layers, with no disruption
between the layers.
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23. Turbulent flow:
fluid moves in very
irregular paths
or zig –zag Way.
efficient mixing.
velocity at a point
fluctuates.
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24. Compressible & Incompressible
flows:
Compressible flow is the branch of fluid
mechanics that deals with flows having
significant changes in fluid density.
Gases, but not liquids, display such
behaviour.
Incompressible flow is the branch of
fluid mechanics which refers the flow in
which the density is constant within a
fluid that moves with a velocity.
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25. Rotational&Irrotational Flow
Rotational flow:
In which the fluid particles while flowing
along stream lines, Also rotate about their
own axis.
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26. Irrotational flow:
In which the fluid particles while flowing
along stream lines, do not rotate about
their own axis.
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27. Viscous and non viscous flow
 A viscous fluid ,such as honey ,does not flow
readily and is said to have a large viscosity.
 In contrast, water is less viscous and flows more
readily;water has a smaller viscosity than honey.
 The flow of viscous fluid is an energy dissipating
process.
 A fluid with zero velocity flows in an unhindered
manner with no dissipation of energy .
 Although no real fluid has zero viscosity at normal
temperatures ,some fluids have negligibly small
velocities.
 An incompressible, non viscous fluid is called an
ideal fluid.
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28. Viscous and non viscous flow
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