This document discusses principles of instrument measurement related to flow measurement. It defines a fluid, describes laminar and turbulent fluid flow, and explains how to calculate the Reynolds number to determine if flow is laminar or turbulent. Key points covered include defining a fluid as a substance that can flow, describing laminar flow as steady and orderly versus turbulent flow as disorderly and time-dependent, and providing the formula and units for Reynolds number along with examples of calculating it to classify flow type.

1. Instrument Measurement
Principles
PHYS6008

2. Flow Measurement

3. Learning Objectives
• When this section is completed the
learner will be able to:
• Explain “What is a fluid?”
• Describe fluid flow
• Differentiate between different types of fluid
flow
• Calculate Reynolds Number

4. What is a fluid?
A fluid is a substance that can
flow – liquids or gases

5. Types of Flow
Laminar Turbulent

6. Types of Flow
Laminar
FLOW PATTERN
• Flow is steady
streamlines
• Particles follow streamlines
• All particles flowing past a point in
the flow will have same velocity Pipe
• Velocity profile is parabolic due
to the frictional forces between
the layers of fluid and between
the fluid and the pipe wall.
VELOCITY PROFILE

7. Types of Flow
Turbulent
FLOW PATTERN
• Flow is disorderly
• At any position in the
flow the velocity is time
dependent and eddies
pipe occur.
• The velocity profile is
more uniform.
• The velocity is 0 ms-1 at
VELOCITY PROFILE
the pipe boundaries.

8. Reynolds Number
What are the units for each parameter?

9. Symbol Units
ρ fluid density kg m-3
v average ms-2
velocity
d pipe m
diameter
η fluid viscosity Nsm-2
What is the unit of the Reynolds number?

11. • If Re > 3000 Turbulent Flow
• If Re = 0 to 2000 Laminar Flow
• For 2000 < Re < 3000 Transition region

12. Example 1
• Oil of density 800 kgm-3 flows with a velocity
of 3.0 ms-1 at 20 0C in a pipe of diameter 300
mm.
• The viscosity of the oil at 20 0C is 0.110 Nsm-2.
• Determine whether the flow is laminar or
turbulent?

13. • If Re > 3000 Turbulent Flow
• If Re = 0 to 2000 Laminar Flow
• For 2000 < Re < 3000 Transition region