FLUID MECHANICS I
MDB 2013
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Course Lecturer:
Dr Mhadi Abaker Ismael
Email:
Mhadi.abaker@utp.edu.my
Phone:
+605-368-7014
Office Address:
Block – 18.03.15
Wed. @ 3:00PM-4:00PM
Contact Hours:
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Course Introduction
Course Objectives (for Fluid Mechanics I)
1.
2.
3.
4.
To introduce the concepts and behavior of fluids in complex
static and flowing condition.
To facilitate the application of fluid mechanics fundamentals
via control volume analysis to address complex engineering
problems.
To present the concept of dimensional analysis in solving
complex engineering problems.
To guide the students on the applications of fluid mechanics
concepts and fundamentals to the design of complex system
involving fluid.
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Course Introduction
Learning Outcomes
towards the end of this course, students should be able to:
1.
2.
3.
4.
Illustrate the concepts and behavior of fluids in static and
flowing condition
Demonstrate the concept and applications of control volume
Apply the knowledge of dimensional analysis
Apply the concepts to the design of simple system involving
fluid
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Introduction to
Fluid Mechanics
~ What is FLUID?
~ What is MECHANICS?
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Introduction
Mechanics:
The oldest physical science that deals with both
stationary and moving bodies under the influence of
forces.
Statics:
The branch of mechanics that deals with bodies at rest.
Dynamics:
The branch that deals with bodies in motion.
Hydrodynamics: The study of the motion of fluids that can be
approximated as incompressible (such as liquids,
especially water, and gases at low speeds).
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Introduction
Hydraulics:
A subcategory of hydrodynamics, which deals with liquid
flows in pipes and open channels.
Gas dynamics:
Deals with the flow of fluids that undergo significant
density changes, such as the flow of gases through
nozzles at high speeds.
Aerodynamics:
Deals with the flow of gases (especially air) over bodies
such as aircraft, rockets, and automobiles at high or low
speeds.
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Fluid Mechanics - Applications
Fluid dynamics is used
extensively in the design of
artificial hearts
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Fluid Mechanics - Applications
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Fluid Mechanics - Applications
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Revision
• In physics, we learnt that a substance exists in
three (3) primary phases:
– solid
– liquid
– gas
How are they distinguished?
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Revision
• Intermolecular bonds
Solid
Solid – molecules are
at relatively fixed
positions
Liquid
Liquid – groups of
molecules move about
each other
Gas
Gas – molecules move
about at random
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Introduction
• What is a fluid and how is it different from a solid?
– Fluid is soft and can easily deformed
– Solid is hard and not easily deformed
Well-described
BUT not too scientific….
• Solids are densely spaced molecules with large intermolecular
cohesive forces that allow the solid to maintain its shape.
• Fluids have molecules that spaced farther apart, the
intermolecular forces are smaller than that of solids and the
molecules have more freedom to move
• Liquids
• Gases
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Introduction
• Characteristics of fluids
• Dimensions, Dimensional Homogeneity and Units
• Analysis of Fluid Behavior
• Measures of fluid mass and weight
• Ideal gas law
• Viscosity
• Compressibility of Fluids
• Vapor pressure
• Surface tension
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Introduction – Characteristics of Fluids
• Solid
– When common solids (e.g. steel) are acted on by a shearing
stress, they will initially deform (usually very small), but will not
continuously deform i.e. flow.
• Fluid
– A substance that deforms continuously when acted on by a
shearing stress of any magnitude.
– Common fluids e.g. water, oil and air satisfy this definition
• Shear stress – force component that acts tangent to the area.
F
Surface
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Introduction – Characteristics of Fluids
• Fluid as a continuum
– Fluid is treated as a continuum which means that the fluid
characteristics of interest (pressure, velocity, etc.) vary
continuously throughout the fluid.
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Introduction – Dimensions,
Dimensional Homogeneity, and Units
• Dimensions – to characterise any physical quantity
• Units – a specific system to quantify numerically the
dimensions of a physical quantity
• Systems of Units – Two (2) systems that are commonly used
in engineering:
• British Gravitational (BG) System
length in foot (ft), time in second (s), force in pound (lb),
temperature in Fahrenheit (°F), absolute temperature in Rankine
(°R)
• International System (SI)
length in meter (m), time in second (s), mass in kilogram (kg),
temperature in Kelvin (K)
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Introduction – Dimensions,
Dimensional Homogeneity, and Units
• Primary dimensions (fundamental dimensions)
Dimension
Unit
Length
meter (m)
Mass
kilogram (kg)
Time
seconds (s)
Temperature
Kelvin (K)
Electric current
ampere (A)
Amount of light
candela (cd)
Amount of matter
mole (mol)
• Secondary dimensions (derived dimensions)
– expressed in terms of primary dimensions
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Introduction – Dimensions,
Dimensional Homogeneity, and Units
Table 1.1.1 Prefix, Symbol and Value
Prefix
peta
tera
giga
Symbol
Value
P
T
G
1015
1012
kilo
M
k
hecto
h
109
106
103
102
deka
da
10
mega
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Introduction – Dimensions,
Dimensional Homogeneity, and Units
Table 1.1.2 Prefix, Symbol and Value
Prefix
centi
milli
Symbol
Value
c
m
10-2
femto
μ
n
p
f
atto
a
micro
nano
pico
10-3
10-6
10-9
10-12
10-15
10-18
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Introduction – Dimensions,
Dimensional Homogeneity, and Units
• Dimensional Homogeneity:
– The dimensions of the left side of all theoretically derived
equations must be the same as those on the right side
– Example:
Equation:
Dimension:
V = Vo + at
LT-1 = LT-1 + (LT-2)T1
– Since the dimensions on the left equal to that on the right, the
equation above is Dimensionally Homogeneous
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Introduction – Dimensions,
Dimensional Homogeneity, and Units
Speed of sound, c
c = kRT
Practice 1:
try to prove the unit on the right hand side of the equation is the same as
that of the left hand side
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Introduction – Analysis of Fluid
Behaviour
Fluid
Mechanics
Fluid Statics
Fluid is at rest
Fluid Dynamics
Fluid is moving
Introduction
• In this lecture, students had seen…
1. The introduction to Fluid Mechanics course
2. The characteristic of fluid
3. Dimensions, Dimensional homogeneity and units in Fluid
Mechanics course
4. Analysis of fluid
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