fluid mechanics · “engineering fluid mechanics” by clayton t. crowe, donald f. elger, barbara...
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FLUID MECHANICS
By
Farhan Ahmad
Department of Chemical Engineering,
University of Engineering & Technology Lahore
2
Course Details
Subject
Subject code
Contact hours
Credit hours
Sessional
Mid term
Final term
Fluid Mechanics
Ch.E - 105
3
3
30 % (Quizzes + Attendance + Class participation + Assignment)
30%
40%
Evaluation procedure
3
Introduction to Fluid Mechanics
Importance of Fluid Mechanics in chemical Engineering
Description of fluids
Types of fluids
Classification of fluid flows
Compressible vs Incompressible Fluids
Steady and Unsteady fluid flow
Properties of Fluids
Course Outline (1)
Basic equations of fluid flow
Flow of Incompressible fluids in pipes
Laminar and Turbulent flow in closed channel
Processes of compressible fluids flows
Flow through variable area conduits
Boundary layer concept
Prandtl’s boundary layer equations
Turbulent boundary layers
Dimensional Analysis
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Course Outline (2)
Text Book
Reference
Books
McCabe Warren L., Smith Julian C., Harriott Peter “Unit Operations of Chemical Engineering” 5th Ed. 2001. McGraw Hill Inc.
1. Coulson J.M., Richardson J.F., “Chemical Engineering” Vol-I,
2. Perry Robert H., Green Don W. “Perry’s Chemical Engineering handbook” 7th Ed. 1997. McGraw Hill Inc.
3. “Engineering Fluid Mechanics” by Clayton T. Crowe, Donald F.
Elger, Barbara C. Williams, John A. Roberson., ed. 9.
4. “Fluid Mechanics Fundamentals and Applications” by Yunus A.
Cengel, John M. Cimbala
5. “Fluid Flow for Practicing Chemical Engineer” by J. Patrick
Abulencia, Louis Theodore
Recommended Books
6
Text book
“Unit Operations of Chemical Engineering” 5th Ed. By Warren L. McCabe, Julian C. Smith & Peter Harriott
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“Chemical Engineering” volume 1
By J. M. Coulson and J. F. Richardson & with J. R. Backhurst and J. H. Harker
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What ……..……………………… ???
Why …………………………….. ???
How …………………………….. ???
When ……………………………. ???
Who …........................................ ???
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Ordinary homes
Water pipelines
Gas pipelines
Sewerage system
air conditioning/heating system
Domestic systems
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Country-wide natural gas transmission system
SNGPL
SSGPL
Industrial Complex piping system
Commercial Applications
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doesn’t permanently resist distortion
Fluid is a substance:
Capable of flowing.
Which cannot preserve its shape unless it is restricted into a
particular vessel.
A fluid in equilibrium cannot sustain any shear.
Liquid
Gases
Fluid
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System of Units
SI Units
CGS Units
FPS Engineering Units
Unit conversions
Consistency
Homogeneity
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o Density
o Viscosity
o Kinematic Viscosity
Viscosity of gases
Viscosity of liquids
o Specific Volume
o Specific Gravity
Concepts
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o Fluid Statics
o Hydrostatic equilibrium
o System, Control volume, Control surface
o Pressure
Concepts
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o Uniform vs Non-uniform flow
o Steady vs unsteady flow
o Laminar vs Turbulent flow
o Uni-dimensional vs Multi-dimensional flow
Concepts
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(a) Laminar flow, in which fluid layers move smoothly over one another in the direction of flow, and
(b) Turbulent flow, in which the flow pattern is complex and time-dependent, with considerable motion perpendicular to the principal flow direction.
Laminar vs Turbulent Flow
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o External forces
o Internal forces
o Shear stress
o Velocity Gradient
o Relationship b/w Shear stress and Velocity gradient
Concepts
Viscosity is that property of a fluid due to which it offers resistance to the movement of one layer of fluid over another adjacent layer of fluid.
Viscosity (μ) is the measure of the resisting forces of a fluid which is being deformed.
Viscosity
For gases,
(for air)
0.9 (for carbon dioxide and simple hydrocarbons)
1.1 (for sulfur dioxide and steam)
Viscosity of gases
The viscosity of a gas is almost independent of pressure in the region of pressures where the gas laws apply.
In this region, the viscosity of gases are generally between 0.01 and 0.1 cP.
At high pressures, gas viscosity increases with pressure.
Determine the viscosities of following fluids (at 1 atm);
Air at 180 oF
Air at 30 oC, 100 oC and 200 oC
CO at 0 oC, 300 oC and 600 oC
Helium at 0 oC, 300 oC and 600 oC
F2, Cl2, Br2 and I2 at 20 oC
Methane, Ethane, Propane, n-Butane, n-Pentane and n-Hexane at 20 oC
The viscosities of liquids are generally much greater than those of gases and cover several orders of magnitude.
Liquid viscosities decrease significantly when the temperature is raised.
For example, the viscosity of water falls from 1.79 cP at 0 oC to 0.28 cP at 100 oC.
The viscosity of a liquid increases with pressure, but the effect is generally insignificant at pressures less than 40 atm.
The absolute viscosities of fluids vary over an enormous range of magnitudes, from about 0.1 cP for liquids near their boiling point to as much as 106 P for polymer melts.
Viscosity of Liquids
Determine the viscosities of following fluids (at 1 atm);
Water at 10 oC.
100% Glycerol at 60 oC.
Propyl Alcohol at 30 oC.
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o Types of fluids
o Newtonian fluids
o Non-Newtonian fluids
o Classification of Non-Newtonian fluids
o Time Independent
o Time dependent
o Viscoelastic fluids
Concepts