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MODULE 1. FLUIDS MECHANICS
MODULE 2. PROPERTIES OF FLUIDS
MODULE 3. PRESSURE AND ITS MEASUREMENT
MODULE 4. PASCAL’S LAW
MODULE 5. PRESSURE FORCES ON PLANE AND CURVED SUR...
MODULE 6.
MODULE 7. BUOYANCY, METACENTRE AND METACENTRIC HEI...
MODULE 8. KINEMATICS OF FLUID FLOW
MODULE 9: CIRCULATION AND VORTICITY
MODULE 10.
MODULE 11.
MODULE 12, 13. FLUID DYNAMICS
MODULE 14.
MODULE 15. LAMINAR AND TURBULENT FLOW IN PIPES
MODULE 16. GENERAL EQUATION FOR HEAD LOSSDARCY EQ...
MODULE 17.
MODULE 18. MAJOR AND MINOR HYDRAULIC LOSSES THROUG...
MODULE 19.
MODULE 20.
MODULE 21. DIMENSIONAL ANALYSIS AND SIMILITUDE
MODULE 22. INTRODUCTION TO FLUID MACHINERY
Lesson13: FLOW VISUALIZATION
13.1 Types of FLUID flow
13.1.1 Uniform flow
Flow velocity is the same magnitude and direction at every point in the fluid.
13.1.2 Nonuniform flow
If at a given instant, the velocity is not the same at every point the flow. (In practice, by this definition, every fluid that flows near a solid boundary will be nonuniform  as the fluid at the boundary must take the speed of the boundary, usually zero. However if the size and shape of the of the crosssection of the stream of fluid is constant the flow is considered uniform.)
13.1.3 Steady flow
A steady flow is one in which the conditions (velocity, pressure and crosssection) may differ from point to point but DO NOT change with time.
13.1.4 Unsteady flow
If at any point in the fluid, the conditions change with time, the flow is described as unsteady. (In practice there is always slight variations in velocity and pressure, but if the average values are constant, the flow is considered steady.)
13.1.5 Steady uniform flow
Conditions: do not change with position in the stream or with time.
Example: the flow of water in a pipe of constant diameter at constant velocity.
13.1.6 Steady nonuniform flow
Conditions: change from point to point in the stream but do not change with time.
Example: flow in a tapering pipe with constant velocity at the inletvelocity will change as you move along the length of the pipe toward the exit.
13.1.7 Unsteady uniform flow
At a given instant in time the conditions at every point are the same, but will change with time.
Example: a pipe of constant diameter connected to a pump pumping at a constant rate which is then switched off.
13.1.8 Unsteady nonuniform flow
Every condition of the flow may change from point to point and with time at every point.
Example: waves in a channel.
13.1.9 Laminar flow
All the particles proceed along smooth parallel paths and all particles on any path will follow it without deviation.
Hence all particles have a velocity only in the direction of flow.
13.1.10 Turbulent Flow
The particles move in an irregular manner through the flow field.
Each particle has superimposed on its mean velocity fluctuating velocity components both transverse to and in the direction of the net flow.
13.1.11 Transition Flow

Exists between laminar and turbulent flow.

In this region, the flow is very unpredictable and often changeable back and forth between laminar and turbulent states.

Modern experimentation has demonstrated that this type of flow may comprise short ‘burst’ of turbulence embedded in a laminar flow.

Rotational flow is the type of flow in which the fluid particles while flowing along streamlines also rotate about their own axis.

Irrotational flow is the type of flow in which the fluid particles while flowing along streamlines do not rotate about their own axis.
13.1.12 Compressible or Incompressible flow

All fluids are compressible  even water  their density will change as pressure changes.

Under steady conditions, and provided that the changes in pressure are small, it is usually possible to simplify analysis of the flow by assuming it is incompressible and has constant density.

As you will appreciate, liquids are quite difficult to compress  so under most steady conditions they are treated as incompressible.
13.1.13 One, Two or Threedimensional Flow

In general, all fluids flow threedimensionally, with pressures and velocities and other flow properties varying in all directions.

In many cases the greatest changes only occur in two directions or even only in one.

In these cases changes in the other direction can be effectively ignored making analysis much more simple.

Flow is one dimensional if the flow parameters (such as velocity, pressure, depth etc.) at a given instant in time only vary in the direction of flow and not across the crosssection. The flow may be unsteady, in this case the parameter vary in time but still not across the crosssection.

Flow is twodimensional if it can be assumed that the flow parameters vary in the direction of flow and in one direction at right angles to this direction.
13.1.14 ROTATIONAL AND IRROTATIONAL FLOWS

Rotational flow is the type of flow in which the fluid particles while flowing along streamlines also rotate about their own axis.

Irrotational flow is the type of flow in which the fluid particles while flowing along streamlines do not rotate about their own axis.