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Lamar UniversityLamar University

Fall 2011Fall 2011

ME 3311 Fluid MechanicsME 3311 Fluid Mechanics

Introduction to Fluid MechanicsIntroduction to Fluid Mechanics

XianchangXianchang LiLi

Department of Mechanical EngineeringDepartment of Mechanical Engineering

Lamar UniversityLamar University

xli2@lamar.eduxli2@lamar.edu

880880--87748774

Introduction

Why do we need to study

Fluid Mechanics?

Because

? No idea or for fun only?

we need to pass it so that we can graduate

it has a wide range of applications

it will benefit our future job

Introduction (2)

What is fluid?

Water, air, oil, natural gas, Freon,

A substance that deforms continuously when there is

a shearing force/stress acting on one of its surface

What is fluid mechanics?

To explain the behavior of fluids at rest & in motion

Classified intofluid statics andfluid dynamics

fluid statics dealing with fluids @ rest

fluid dynamics dealing with fluids in motion

Introduction (3)

Potential applications

Aerodynamics

Hydrodynamics

Power generation

Chemical process

Bio-engineering

HVAC

Meteorology

Sports

Aerodynamics

Questions:

How and why is the

body shape/profile

designed in this way?

What force makes

the airplane fly?

How to determine

the power needed?

Aerodynamics (2)

Questions:

Why the warplane

has a sharp nose?

Why people cannot

fly as birds?

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Hydrodynamics

Questions: Power needed? Shape? Pressure to overcome?

Meteorology

Questions: How the air moves? Why there is a hurricane?

Power Generation

Questions: What is this?

How does it work?

How to improve the efficiency?

Power Generation (2)

Questions:

How does it work?

Why do we need water flow?

Power Generation (3)

Questions:

How strong should the dam be?

How to calculate the force on the dam?

Power Generation (4)

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Chemical Engineering

Questions:

How & why do the fluids flow in the

pipes?

How big does the pumps need to be?

Bio Engineering

HVAC

Questions:

What size should the air duct be? How to uniformly distribute the

air among different rooms?

Sports

Questions:

What is the purpose of

dimples on the golf ballsurface?

Spoil on a race car? How

does it work and why?

Some Extra Ones

Supersonic flows result in shock

waves A big concern to design

high-speed warplanes

The plume of volcano eruption (Mt. St.

Helens in 1980) involves gas, liquid,

and solid particles. Strong turbulence

can be seen.

More Details of Fluid Mechanics for Automobiles

Exterior shape design Streamlined body to reduce drag

Fuel system Right flow rate, pressure, spraying

Cooling water/coolant loop To maintain the engine

temperature. Is there any pump in use?

Exhaust/intake air flow design

Flow around the radiator How powerful should the fan

be? Is there any difference when the car has a different

speed?

Lubrication/bearing

Engine oil What kind of properties are desired?

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Fluid Mechanics Is Everywhere Fluid Mechanics is Beautiful

Fluid Mechanics is Beautiful (2) Beautiful but Tough

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Partial differential equations governing the flow

Turbulence needs to be modeled

Some Important Issues about the Course

Homework 10%

Pop Quizzes 10%

Exams (2) 35% (15%, 20%)

Project 15%

Final (Comprehensive) 30%

90~100% -- A

80~89% -- B or better

70~79% -- C or better

60~69% -- D or better

0~59% -- F

Important Issues about the Course (2)

Attendance is required. Students are responsible for

all the work missed due to their absence. Students

with perfect attendance will receive 5 bonus points

toward their final score. The bonus points will be

deducted for each unexcused absence.

Late papers (Homework & Projects) will receive 50%

credit before the grading starts and 0% after that.

Makeup exams (with an approved reason) can receive

a maximum of 75% points before the solutions are

given and 0% after that.

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Let the Dream Come True The End

Questions and comments ?