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8/10/2019 Chapter 1 Fluid Properties2013
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CHE493: FLUID MECHANICS
ATIKAH KADRIOFFICE: PAA1110A
1) Lesson Plan
2) Entrance Survey Form
Course Outcome 1: Identify properties of fluids and various
types of fluid measuring devices.
Course Outcome 2: Develop knowledge on fluids through
friction in pipes, channels and fluid motive
devices.Course Outcome 3: Apply the knowledge in solving fluid
mechanics related problem.
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Applied mechanics concerned with statics and
dynamics of fluids.
Analysis of the behavior of fluids is based on
the fundamental laws of mechanics.
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Chapter 1: FLUID PROPERTIES
Define the nature of a fluid.
Observe fluid mechanics concepts.
Introduce viscosity.
Define appropriate physical properties.
What is fluid?
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FLUID:
Substances in gases or liquid. What these two
has in common? In contrast to solids they are lack the ability to
resist deformation.
SOLID FLUID
Can resist an applied shear by deforming
not continue to move indefinitely.
Deforms continuously under applied shear
it flows under the action of the forces.
Shape changes continuously.
Stress is proportional to strain (independent
of time). The deformation disappear when
the force is removed
Stress is proportional to strain rate. Original
form will not be recovered when the force is
removed
Difference between Solid and Fluid
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SOLID FLUID
Shear stress,
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Properties of Fluids
Intensive properties: independent of the mass
of the system, EgT, P, density.
Extensive properties: depends on the size of
the system, Egtotal mass, total volume,
total momentum.
Specific propertiesextensive properties per
unit mass, Egspecific gravity, specific
weight.
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Units & Dimensions
Unit is a way to assign a number ormeasurement to a dimension.
SI (International system) units
B.G. (British Gravitational system)
Basic dimension used in Fluid Mechanics
Quantity SI unit BG Unit Dimension
Length meter, m foot, ft L
Mass kilogram, kg slug M
Temperature kelvin, K rankine, R
Time second, s second, s T
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Density,
Changes with temperature and pressure,
especially on gases.
Unit
Specific weight,
The force exerted by gravity upon a unit volume of thesubstance.
Unit
water = , air= 12.07
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Ratio of density of a substance to a density of
water at 4o
C. SG of Mercury = 13.6
Unit ?
SG of water? SG of air?
Specific Gravity, SG
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EXAMPLE
A reservoir of glycerin has a mass of 1200 kg
and a volume of 0.952 m3. Determine the
glycerins weight, density and specific gravity.
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Activity
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Viscosity
Viscosity : measurement of fluid resistance towards deformation.: resistance to flow, shearing stress.
: water vs honey
Shear Stress: Tangential force per unit area.
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Two large, parallel plates with a small distance, y apart.
The space between the plates being filled with fluid
Keep upper plate moving at constant velocity, u by applying
a constant force, F tangential to the area of the plate. Thus there must be a viscous interaction between plate and
fluid.
Fluid in contact with upper plate will adhere to it and willmove at velocity, u.
Fluid in contact with the fixed plate will have velocity = 0 If y and u are not too great, velocity profile will be a
straight line (laminar flow).
From experiment , Shear Force, F :
Varies with area of the plate
Varies with velocity, u
Varies Inversely with distance, y
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(Newtons Law of Viscosity)
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