chapter 1 fluid mechanics
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FLUID MECHANICSCLD 10603
Introduction to Fluid Systems
Yushazaziah Mohd YunosSection of Chemical Engineering Technology
UNIKL – MICET
ObjectivesAt the end of this chapter, you should be able to : Define fluid Classify the type of fluid and its physical
behaviors. Know examples of fluid system.
CLD 10603 2 Chapter 1: Introduction to Fluid Systems
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
Fluid mechanics is a branch in applied mechanics concerned to the behaviour of liquid or gas which is either in rest or in motion.
The study related to a fluid in rest or stationary is referred to fluid static (rest), otherwise it is referred to as fluid dynamic (motion).
Introduction
Chapter 1: Introduction to Fluid Systems
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
CLD 10603 3
A continuous amorphous substance that tends to flow and to conform to the outline of its container. It does can deform continuously when being subjected to shear stress at any magnitude. This includes any liquid or gas.
Definition of Fluid
Chapter 1: Introduction to Fluid Systems
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
CLD 10603 4
Stress is defined as the force per unit area.
Normal component: normal stresso In a fluid at rest, the
normal stress is called pressure
Tangential component: shear stress
Definition of Fluid
Chapter 1: Introduction to Fluid Systems
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
CLD 10603 5
Fluid Solid The rate of strain is proportional to the applied stress.
The strain is a function of the applied stress, providing that the elastic limit is not exceeded.
A fluid continues to flow as long as the force is applied and will not recover its original form when the force is removed.
The strain in a solid is independent of the time over which the force is applied and, if the elastic limit is not exceeded, the deformation disappears when the force is removed
Chapter 1: Introduction to Fluid Systems
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
Distinctions between Fluid and Solid
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Liquid Gas Liquid is difficult to compress and often regarded as being incompressible.
A gas is easily to compress and usually treated as such - it changes volume with pressure.
A given mass of liquid occupies a given volume and will occupy the container it is in and form a free surface (if the container is of a larger volume).
A gas has no fixed volume, it changes volume to expand to fill the containing vessel. It will completely fill the vessel so no free surface is formed.
Chapter 1: Introduction to Fluid Systems
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
Distinctions between Fluid and Gas
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Solid are tightly packed, usually in a regular pattern. It’s vibrate (jiggle) but generally do not move from place to place.
For liquids, it is stronger which is sufficient enough to hold the molecule together and can withstand high compression, which is suitable for application as hydraulic fluid such as oil. On the surface, the cohesion forms a resultant force directed into the liquid region and the combination of cohesion forces between adjacent molecules form a tensioned membrane known as free surface.
For gases, it is very weak which enables the gas to disintegrate and move away from its container.
Chapter 1: Introduction to Fluid Systems CLD 10603 8
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
Solid, liquid, Gas
(a) Solid (b) Liquid (c) Gas
k
k k
k
Free surface
Newtonian Fluid – all fluids in which shear stress is directly proportional to the deformation rate.
Example: Water, air and gasoline.
Non Newtonian Fluid – All fluids in which shear stress is indirectly proportional to deformation rate.
Example: Toothpaste and Paint.
Chapter 1: Introduction to Fluid Systems CLD 10603 9
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
Classification of Fluid
dy
duyx
• Bingham Plastic: toothpaste• Pseudoplastic : paint, polymer
solutions• Newtonian Fluid : water, air
• Dilatant : quicksand, solutions with suspended starch or sand
Chapter 1: Introduction to Fluid Systems CLD 10603 10
Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
Classification of Fluid
Many of them can be found in:
Home or school
- Heating and air conditioning, water supply and liquid waste removal, personal computer cooling system, refrigerator, fan, vacuum cleaner, hair dryer etc.
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Universiti Kuala Lumpur Malaysian Institute of Chemical and Bioengineering technology
Examples of Fluid System
Outside environment
- Road and rail vehicles, airplanes , ship, water reservoir and air ducts, municipal waste treatment plants, incinerators etc.
Industrial system
- Hydraulic power system for construction and manufacturing equipments, catalytic crackers in petroleum refineries.
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Examples of Fluid System
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Natural Environment
Tornadoes Thunderstorm
Global Climate Hurricanes
The aim - to find low drag body shapes and reduce fuel and electrical energy consumptions.
1930’s – 17 passengers with 250 km/h Boeing 707 Wind tunnel model A340 (300 km/h)
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Transportations
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Transportations
Trains
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Cars – Mercedes-Benz
Racing car
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Physiology and Medicine
Blood pump Ventricular assist device
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Sports & Recreation
Water sports
Auto racing
Offshore racingCycling
Surfing