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```					Seminar Report ‟05                                                  Aerodynamics In Cars

ABSTRACT

When objects move through air, forces are generated by the relative
motion between the air and surfaces of the object. Aerodynamics is the study of these
forces, generated by the motion of air, usually aerodynamics are categorized according to
the type of flow as subsonic, hypersonic, supersonic etc.

It is essential that aerodynamics be taken in to account during the
design of cars as an improved aerodynamics in car would attain higher speeds and more
fuel efficiency. For attaining this aerodynamic design the cars are designed lower to the
ground and are usually sleek in design and almost all corners are rounded off, to ensure
smooth passage of air through the body , in addition to it a number of enhancements like
spoilers, wings are also attached to the cars for improving aerodynamics. Wind tunnels
are used for analyzing the aerodynamics of cars , besides this a number of software‟s are
also available now days to ensure the optimal aerodynamic design.
Seminar Report ‟05                                      Aerodynamics In Cars

CONTENTS

Acknowledgement
Abstract
Contents
List of figures
1. Introduction
2. Aerodynamic forces on a body
a) Lift
b) Weight
c) Drag
d) Thrust

3. History and evolution of aerodynamics
4. Study of Aerodynamic forces on cars
a) Drag
b) Lift or Downforce
5. Aerodynamic devices
6. Drag Coefficiant
7. Methods for evaluating Aerodynamics in cars
a) Wind tunnels
b)     Softwares
8. Aerodynamic Design tips
9. conclusions
10. References
Seminar Report ‟05                                                   Aerodynamics In Cars

INTRODUCTION

When objects move through air, forces are generated by the
relative motion between air and surfaces of the body, study of these forces generated by
air is called aerodynamics. Based on the flow environment it can be classified in to
external aerodynamics and internal aerodynamics; external aerodynamics is the flow
around solid objects of various shapes, where as internal aerodynamics is the flow
through passages in solid objects, for e.g. the flow through jet engine air conditioning
pipe etc. The behavior of air flow changes depends on the ratio of the flow to the speed
of sound. This ratio is called Mach number, based on this mach number the aerodynamic
problems can be classified as subsonic if the speed of flow is less than that of sound,
transonic if speeds both below and above speed of sound are present, supersonic if
characteristics of flow is greater than that of sound and hypersonic if flow is very much
greater than that of sound. Aerodynamics have wide range of applications mainly in
aerospace engineering ,then in the design of automobiles, prediction of forces and
moments in ships and sails, in the field of civil engineering as in the design of bridges
and other buildings, where they help to calculate wind loads in design of large buildings.
Seminar Report ‟05                                                        Aerodynamics In Cars

AERODYNAMIC FORCES ON A BODY

Fig 1

LIFT

It is the sum of all fluid dynamic forces on a body normal to the direction
of external flow around the body. Lift is caused by Bernoulli‟s effect which states that air
must flow over a long path in order to cover the same displacement in the same amount
of time. This creates a low pressure area over the long edge of object as a result a low
pressure region is formed over the aerofoil and a high pressure region is formed below
the aerofoil, it is this difference in pressure that creates the object to rise
F=(1/2)CLdV2A
Where :
CL= Coefficient of Lift, dependent on the specific geometry of the object,
determined experimentally
d= Density of air
V=Velocity of object relative to air, A=Cross-sectional area of object, parallel to wind
Seminar Report ‟05                                                      Aerodynamics In Cars

DRAG

It is the sum of all external forces in the direction of fluid flow, so it acts
opposite to the direction of the object. In other words drag can be explained as the force
caused by turbulent airflow around an object that opposes the forward motion of the
object through a gas or fluid.

F=(1/2)CDdV2A

where: CD= Coefficient of Drag, dependent on the specific geometry of the object,
determined experimentally.
d= Density of air.
V=Velocity of object relative to air.
A= cross section of frontal area.
Since drag is dependent on square of velocity it is most predominant
when object is traveling at very high speeds. It is the most important aerodynamic force
to study because it limits both fuel economy of a vehicle and the maximum speed at
which a vehicle can travel.

WEIGHT

It is actually just the weight of the object that is in motion.i.e. the mass of the
object multiplied by the magnitude of gravitational field.This weight has a significant
effect on the acceleration of the object.
THRUST

When a body is in motion a drag force is created which opposes the motion of
the object so thrust can be the force produce in opposite direction to drag that is higher
than that of drag so that the body can move through the fluid. Thrust is a reaction force
explained by Newton‟s second and third laws, The total force experienced by a system
accelerating in mass “m” is equal and opposite to mass “m” times the acceleration
experienced by that mass.
Seminar Report ‟05                                                     Aerodynamics In Cars

HISTORY & EVOLUTION OF AERODYNAMICS

Ever since the first car was manufactured in early 20th century the
attempt has been to travel at faster speeds, in the earlier times aerodynamics was not a
factor as the cars where traveling at very slow speeds there were not any aerodynamic
problems but with increase of speeds the necessity for cars to become more streamlined
resulted in structural invention such as the introduction of the windscreen, incorporation
of wheels into the body and the insetting of the headlamps into the front of the car. This
was probably the fastest developing time in automobiles history as the majority of the
work was to try and reduce the aerodynamic drag. This happened up to the early 1950‟s,
where by this time the aerodynamic dray had been cut by about 45% from the early cars
such as the Silver Ghost. However, after this the levels of drag found on cars began to
slowly increase. This was due to the way that the designing was thought about.
Before1950, designers were trying to make cars as streamlined as possible to make it
easier for the engine, yet they were restricting the layout of the interior for the car. After
1950, the levels of aerodynamic drag went up because cars were becoming more family
friendly and so as a consequence the shapes available to choose were more limited and
so it was not possible to keep the low level of aerodynamic drag. The rectangular shape
made cars more purposeful for the family and so it is fair to say that after 1950 the
designing of cars was to aid the lifestyle of larger families.
Although this was a good thing for families, it didn‟t take long before
the issue of aerodynamics came back into the picture in the form of fuel economy.
During the 1970‟s there was a fuel crisis and so the demand for more economical cars
became greater, which led to changes in car aerodynamics. During the 1970‟s there was
a fuel crisis and so the demand for more economical cars became greater, which led to
changes in car aerodynamics. If a car has poor aerodynamics then the engine has to do
more work to go the same distance as a car with better aerodynamics, so if the engine is
working harder it is going to need more fuel to allow the engine to do the work, and
therefore the car with the better aerodynamics uses less fuel than the other car. This
quickly led to a public demand for cars with a lower aerodynamic drag in order to be
more economical for the family.
Seminar Report ‟05                                                    Aerodynamics In Cars

This diagram below shows the typical use of cars energy that it gets,

Fig 2

Only about 15% of the energy from the fuel you put in your tank gets
used to move your car down the road or run useful accessories, such as air conditioning.
The rest of the energy is lost to engine and driveline inefficiencies and idling. Therefore,
the potential to improve fuel efficiency with advanced technologies is enormous.

Now a days almost all cars are manufactured aerodynamically , one
misconception that everyone has is aerodynamics is all about going faster, in a way it is
true but it is not all about speed, by designing the car aerodynamically we can reduce the
friction that it encounters and there by power needed to overcome would be less thus fuel
can be saved; In the modern era where our fuel resources are fast depleting all the efforts
are to find alternate sources of energy or to save our current resources or minimize the
use of current resources like fuels, so now a days aerodynamics are given very much
importance as everyone like to have a good looking , stylish and fuel efficient car.
Seminar Report ‟05                                                      Aerodynamics In Cars

STUDY OF AERODYNAMICS OF CARS

In order to improve the aerodynamics we must first know how the flow of air
past a car, if we visualize a car moving through the air. As we all know, it takes some
energy to move the car through the air, and this energy is used to overcome a force called
Drag.

DRAG

A simple definition of aerodynamics is the study of the flow of air around and
through a vehicle, primarily if it is in motion. To understand this flow, you can visualize
a car moving through the air. As we all know, it takes some energy to move the car
through the air, and this energy is used to overcome a force called Drag.

Drag, in vehicle aerodynamics, is comprised primarily of two forces. Frontal pressure
and rear vaccum.

DRAG FORCE AT LOW SPEEDS

The total drag force decreases, meaning that a car with a low drag force will be
able to accelerate and travel faster than one with a high drag force. This means a smaller
engine is required to drive such a car, which means less consumption of fuel.

CAR WEIGHT

As with the parts inside the engine, when the entire car is made lighter, through
the use of lighter materials or better designs, less force is required to move the car. This
is based on F=MA or more accurately, A=F/M, so as mass of the car decreases, the
acceleration increases, or less force is required to accelerate the lighter car.
Seminar Report ‟05                                                    Aerodynamics In Cars

FRONT END

Fig 3

Frontal pressure is caused by the air attempting to flow around the front of the
car. As millions of air molecules approach the front grill of the car, they begin to
compress, and in doing so raise the air pressure in front of the car. At the same time, the
air molecules traveling along the sides of the car are at atmospheric pressure, a lower
pressure compared to the molecules at the front of the car. The compressed molecules of
air naturally seek a way out of the high pressure zone in front of the car, and they find it
around the sides, top and bottom of the car. Improvements at the front can be made by
ensuring the „front end is made as a smooth, continuous curve originating from the line
of the front bumper‟. Making the screen more raked (ie. not as upright) „tends to reduce
the pressure at the base of the screen, and to lower the drag‟. However, much of this
improvement arrives because a more sloped screen means a softer angle at the top where
it meets the roof, keeping flow attached. Similar results can be achieved through a
suitably curved roofs.
Seminar Report ‟05                                                     Aerodynamics In Cars

This graph clearly shows that drag force is directly proportional to frontal area.(results of
wind tunnel tests)

Fig 4
REAR END

Rear vacuum (a non-technical term, but very descriptive) is caused by the "hole"
left in the air as the car passes through it. To visualize this, imagine a bus driving down a
road. The blocky shape of the bus punches a big hole in the air, with the air rushing
around the body, as mentioned above. At speeds above a crawl, the space directly behind
the bus is "empty" or like a vacuum. This empty area is a result of the air molecules not
being able to fill the hole as quickly as the bus can make it. The air molecules attempt to
fill in to this area, but the bus is always one step ahead, and as a result, a continuous
vacuum sucks in the opposite direction of the bus. This inability to fill the hole left by
the bus is technically called Flow detachment .At the rear of vehicles, the ideal format is
a long and gradual slope. As this is not practical, it has been found that „raising and/or
lengthening the boot generally reduces the drag”. In plan view, rounding corners and „all
Seminar Report ‟05                                                     Aerodynamics In Cars

forward facing elements‟ will reduce drag. Increases in curvature of the entire vehicle in
plan will usually decrease drag provided that frontal area is not increased. „Tapering the
rear in plan view‟, usually from the rear wheel arch backwards, „can produce a
significant reduction in drag‟. Under the vehicle, a smooth surface is desirable as it can
reduce both vehicle drag and surface friction drag. „For a body in moderate proximity to
the ground, the ideal shape would have some curvature on the underside.‟

Fig 5

Flow detachment applies only to the "rear vacuum" portion of the drag equation,
and it is really about giving the air molecules time to follow the contours of a car's
bodywork, and to fill the hole left by the vehicle, The reason keeping flow attachment is
so important is that the force created by the vacuum far exceeds that created by frontal
pressure, and this can be attributed to the Turbulence created by the detachment.

Fig 6
Seminar Report ‟05                                                     Aerodynamics In Cars

LIFT OR DOWNFORCE

One term very often heard in race car circles is Down force. Down force is the
same as the lift experienced by airplane wings, only it acts to press down, instead of
lifting up. Every object traveling through air creates either a lifting or down force
situation. Race cars, of course use things like inverted wings to force the car down onto
the track, increasing traction. The average street car however tends to create lift. This is
because the car body shape itself generates a low pressure area above itself.
For a given volume of air, the higher the speed the air molecules are traveling,
the lower the pressure becomes. Likewise, for a given volume of air, the lower the speed
of the air molecules, the higher the pressure becomes. This of course only applies to air
in motion across a still body, or to a vehicle in motion, moving through still air.
When we discussed Frontal Pressure, above that the air pressure was high as the air
rammed into the front grill of the car. What is really happening is that the air slows down
as it approaches the front of the car, and as a result more molecules are packed into a
smaller space. Once the air Stagnates at the point in front of the car, it seeks a lower
pressure area, such as the sides, top and bottom of the car.
Now, as the air flows over the hood of the car, it's loses pressure, but when it
reaches the windscreen, it again comes up against a barrier, and briefly reaches a higher
pressure. The lower pressure area above the hood of the car creates a small lifting force
that acts upon the area of the hood (Sort of like trying to suck the hood off the car). The
higher pressure area in front of the windscreen creates a small (or not so small) down
force. This is akin to pressing down on the windshield.
Where most road cars get into trouble is the fact that there is a large surface area
on top of the car's roof. As the higher pressure air in front of the wind screen travels over
the windscreen, it accelerates, causing the pressure to drop. This lower pressure literally
lifts on the car's roof as the air passes over it. Worse still, once the air makes it's way to
the rear window, the notch created by the window dropping down to the trunk leaves a
vacuum, or low pressure space that the air is not able to fill properly. The flow is said to
detach and the resulting lower pressure creates lift that then acts upon the surface area of
the trunk.
Seminar Report ‟05                                                    Aerodynamics In Cars

Fig 7
Not to be forgotten, the underside of the car is also responsible for creating lift or down
force. If a car's front end is lower than the rear end, then the widening gap between the
underside and the road creates a vacuum, or low pressure area, and therefore "suction"
that equates to down force. The lower front of the car effectively restricts the air flow
under the car. So, as you can see, the airflow over a car is filled with high and low
pressure areas, the sum of which indicate that the car body either naturally creates lift or
down force.

Fig 8
Seminar Report ‟05                                                     Aerodynamics In Cars

WINGS & SPOILERS

What this wings or spoilers does is it prevents the separation of flow and
there by preventing the formation of vortices or helps to fill the vaccum in the rear end
more effectively thus reducing drag. So what actually this wings does is that, The wing
works by differentiating pressure on the top and bottom surface of the wing. As
mentioned previously, the higher the speed of a given volume of air, the lower the
pressure of that air, and vice-versa. What a wing does is make the air passing under it
travel a larger distance than the air passing over it (in race car applications). Because air
molecules approaching the leading edge of the wing are forced to separate, some going
over the top of the wing, and some going under the bottom, they are forced to travel
differing distances in order to "Meet up" again at the trailing edge of the wing. This is
part of Bernoulli's theory. What happens is that the lower pressure area under the wing
allows the higher pressure area above the wing to "push" down on the wing, and hence
the car it's mounted to.

The way a real, shaped wing works is essentially the same as an airplane wing,
but it's inverted. An airplane wing produces lift, a car wing produces negative lift or in
other words what we call us, downforce. That lift is generated by a difference in pressure
on both sides of the wing. .

But how is the difference in pressure generated? Well, if you look closely at the
drawings, you'll see that the upper side of the wing is relatively straight, but the bottom
side is curved. This means that the air that goes above the wing travels a relatively
straight path, which is short. The air under the wing has to follow the curve, and hence
travel a greater distance. Now there's Bernoulli's law, which basically states that the total
amount of energy in a volume of fluid has to remain constant. (Unless you heat it or
expose an enclosed volume of it to some form of mechanical work) If you assume the air
doesn't move up and down too much, it boils down to this: if air (or any fluid, for that
matter) speeds up, its pressure drops. From an energetic point of view, this makes sense:
Seminar Report ‟05                                                    Aerodynamics In Cars

if more energy is needed to maintain the speed of the particles, there's less energy left do
do work by applying pressure to the surfaces.

In short: on the underside, air has to travel further in the same amount of time,
which means it has to speed up, which means its pressure drops. More pressure on top of
the wing and less on the underside results in a net downward force called downforce.

AERODYNAMIC DEVICES

SCOOPS

Fig 9

Scoops, or positive pressure intakes, are useful when high volume air flow is
desirable and almost every type of race car makes use of these devices. They work on the
principle that the air flow compresses inside an "air box", when subjected to a constant
flow of air. The air box has an opening that permits an adequate volume of air to enter,
and the expanding air box itself slows the air flow to increase the pressure inside the box.
See the diagram below:
Seminar Report ‟05                                                    Aerodynamics In Cars

Fig 10

NACA Ducts

NACA stands for "National Advisory Committee for Aeronautics". NACA is
one of the predecessors of NASA. In the early days of aircraft design, NACA would
mathematically define airfoils (example: NACA 071) .

Fig 11

The purpose of a NACA duct is to increase the flowrate of air through it while
not disturbing the boundary layer. When the cross-sectional flow area of the duct is
increased, you decrease the static pressure and make the duct into a vacuum cleaner, but
without the drag effects of a plain scoop. The reason why the duct is narrow, then
suddenly widens in a graceful arc is to increase the cross-sectional area slowly so that
airflow does separate and cause turbulence (and drag).

NACA ducts are useful when air needs to be drawn into an area which isn't
exposed to the direct air flow the scoop has access to. Quite often you will see NACA
ducts along the sides of a car. The NACA duct takes advantage of the Boundary layer, a
layer of slow moving air that "clings" to the bodywork of the car, especially where the
bodywork flattens, or does not accelerate or decelerate the air flow. Areas like the roof
and side body panels are good examples. The longer the roof or body panels, the thicker
the layer becomes (a source of drag that grows as the layer thickens too). Anyway, the
NACA duct scavenges this slower moving area by means of a specially shaped intake.
The intake shape, shown below, drops in toward the inside of the bodywork, and this
draws the slow moving air into the opening at the end of the NACA duct. Vortices are
Seminar Report ‟05                                                      Aerodynamics In Cars

also generated by the "walls" of the duct shape, aiding in the

scavenging. The shape and depth change of the duct are critical for proper operation.

Fig 12

SPOILERS

Spoilers are used primarily on sedan-type race cars. They act like barriers to air
flow, in order to build up higher air pressure in front of the spoiler. This is useful,
because as mentioned previously, a sedan car tends to become "Light" in the rear end as
the low pressure area above the trunk lifts the rear end of the car. See the diagram below:

Fig 13

Front air dams are also a form of spoiler, only their purpose is to restrict the air flow
from going under the car.

WINGS

Probably the most popular form of aerodynamic aid is the wing. Wings perform
very efficiently, generating lots of down force for a small penalty in drag. Spoiler are not
nearly as efficient, but because of their practicality and simplicity, spoilers are used a lot
Seminar Report ‟05                                                     Aerodynamics In Cars

on sedans.

The wing works by differentiating pressure on the top and bottom surface of the wing.
As mentioned previously, the higher the speed of a given volume of air, the lower the
pressure of that air, and vice-versa. What a wing does is make the air passing under it
travel a larger distance than the air passing over it (in race car applications). Because air
molecules approaching the leading edge of the wing are forced to separate, some going
over the top of the wing, and some going under the bottom, they are forced to travel
differing distances in order to "Meet up" again at the trailing edge of the wing. This is
part of Bernoulli's theory.

What happens is that the lower pressure area under the wing allows the higher pressure
area above the wing to "push" down on the wing, and hence the car it's mounted to. See
the diagram below:

Fig 14

Wings, by their design require that there be no obstruction between the
bottom of the wing and the road surface, for them to be most effective. So
mounting a wing above a trunk lid limits the effectiveness.

DRAG COEFFICIANT

To calculate the aerodynamic drag force on an object, the following formula can be used:

Where:
F - Aerodynamic drag force
F = ½ CDAV²
C - Coefficient of drag
D - Density of air
Seminar Report ‟05                                                 Aerodynamics In Cars

A - Frontal area
V - Velocity of object

In this system, D as air density is expressed in kg/m³. The frontal area is the surface of

the object viewed from a point that object is going to. It's expressed in m³. The
better(lower) the number is the easier it is for air to pass around a car

Fig 15

It is the measure of the aerodynamic efficiency of the car .

.
Seminar Report ‟05                                                     Aerodynamics In Cars

METHODS FOR EVALUATING AERODYNAMCIS OF CARS

WIND TUNNELS

A wind tunnel is a research tool developed to assist with studying the effects
of air moving over or around solid objects. Air is blown or sucked through a duct
equipped with a viewing port and instrumentation where models or geometrical shapes
are mounted for study. Various techniques are then used to study the actual airflow
around the geometry and compare it with theoretical results, which must also take into
account the Reynolds number and Mach number for the regime of operation. Threads
can be attached to the surface of study objects to detect flow direction and relative speed
of air flow.
Dye or smoke can be injected upstream into the airstream and the streamlines that dye
particles follow photographed as the experiment proceeds.
Traditionally, wind tunnel testing was a sizeable trial and error process, ongoing
throughout the development of a vehicle. Today, with the high level of CAD prediction
and pre-production evaluation, coupled with a greater human understanding of
aerodynamics, wind tunnel testing often comes into the design process later. The wind
tunnel is the proving ground for the vehicle's form and allows engineers to obtain
considerable amounts of advanced information within a controlled environment.
Seminar Report ‟05            Aerodynamics In Cars

Fig 16
Seminar Report ‟05                                                    Aerodynamics In Cars

Now a days the aerodynamic studies are not constrained to the flow of air past
cars but also a number of other factors like new methods are developed to provide a
greater level of detailed information. Special pressure sensitive paint is now used in the
wind tunnel to graphically show levels of air pressure on a vehicle how it is done is that
,Two different images are obtained, one at normal room air pressure (wind-off) and a
second in which the wind tunnel is running (wind-on) at a desired test speed. These
differences in color, from wind-off to wind-on, are used to calculate surface pressure.
A bank of blue lights illuminate the car to be tested that has pressure-sensitive
paint applied on the driver's side window. The car and lights are in a wind tunnel at Ford
Motor Company's Dearborn Proving Ground. Ford researchers have developed a
computerized, pressure-sensitive paint technique that measures airflow over cars,
shaving weeks off current testing methods. A digital camera near the blue lights captures
this information and feeds it into a computer, which displays the varying pressure as
dramatically different colors on a monitor.
The images obtained from tests in the wind tunnel are captured on computer.
They can then be used to study air flow patterns across a vehicle, highlighting areas of
model can be compared with pre-production computer predictions which can in turn help
improve the accuracy of the early design stages.

SOFTWARES

Now a days a large number of software‟s are developed for the analysis and
optimization of aerodynamics in automobiles. Earlier times the cars were worked
directly on wind tunnels where they prepared different shapes or cross sections and
tested upon the cars, during those times it was not possible to test the for small areas that
is for a small part of front area etc there testing were made for the entire cross sections,
But with the introduction of computational fluid dynamics i.e. the use of computers to
analyze fluid flows where the entire area is divided in to grids and each grid is analyzed
and suitable algorithms are developed to solve the equations of motion.Based on CFD
large number of software‟s are developed for the design and analyzing aerodynamics the
Seminar Report ‟05                                                     Aerodynamics In Cars

most commonly used software‟s are ANSYS,CATIA.
Here are some of the features of commonly used software Alias surface studio

ALIAS SURFACE AND AUTO STUDIO

Alias Surface Studio is a technical surfacing product designed for the
development surfaces. It offers advanced modeling and reverse engineering tools, real-
time diagnostics and scan data processing technology. Surface Studio is comprised of a
complete suite of tools for creating surface models to meet the high levels of quality,
accuracy and precision required in automotive styling.
This software performs all the basics of design right from the sketching to
evaluation.

Features:
1)User Interaction
A user interface that enables creativity and efficiency

2) Sketching
A complete set of tools for 2D design work tightly integrated into a 3D modeling
environment
3)2D / 3D Integration
and explore ideas quickly by sketching over 3D forms before taking the time to model
them.
4) Modeling
Surface creation tools that maintain positional, tangent or curvature continuity
between surfaces - for high quality, manufacturability results.
6) Reverse Engineering
Tools for importing and configuring cloud data sets from scanners for visualizing,
as well as extracting feature lines and building surfaces based on cloud data.
Seminar Report ‟05                                                    Aerodynamics In Cars

7) Evaluation Tools
Tools to analyze and evaluate the styling and physical properties of curves and
surfaces interactively, while creating and editing geometry.
8)Rendering
Create photorealistic images using textures, colours, highlights, shadows,
reflections and backgrounds.
9)Animation
Animations can be used for high quality design presentations, design analysis of
mechanisms, motion and ergonomic studies, manufacturing or assembly simulation.
10)DataIntegration
Support for industry-standard data formats and a wide range of peripheral
devices.These software‟s are now commonly in use as wind tunnel testing is an
expensive process as compared to this software‟s where we get more accurate and easily
the test results.

AERODYNAMIC DESIGN TIPS

.) Keep the vehicle low to the ground, with a low nose, and pay attention to
the angle of wind shield.
.) Cover the wheel wells, Open wheels create a great deal of drag and air flow turbulence
.) Enclose the under carriage (avoid open areas-convertibles, etc.)
.) Make corners round instead of sharp

.) The underbody should be as smooth and continuous as possible, and should sweep out
slightly at rear.

.) There should be no sharp angles (except where it is necessary to avoid crosswind
instability ).

.) The front end should start at a low stagnation line, and curve up in a continuous line.
Seminar Report ‟05                                                   Aerodynamics In Cars

.) The front screen should be raked as much as is practical.

. ) All body panels should have a minimal gap.

.) Glazing should be flush with the surface as much as possible.

.) All details such as door handles should be smoothly integrated within the contours.

.) Minor items such as wheel trims and wing mirrors should be optimized using wind
tunnel testing.

.) Using spoilers or wings.

FOR A VEHICLE YOU ALREADY OWN

• Keep your vehicle washed and waxed. This reduces skin friction.
• Remove mud flaps from behind the wheels.
• Add a spoiler to the front fender or the rear of the car. Having it on the front fender
reduces air flow beneath the car, while having it behind will decrease the low pressure
behind the car and reduce drag.
• Avoid having roof-racks and carriers on your car.
• For pickups: cover the back, take the gate off, or at least leave the gate open. Air gets
trapped in the bed and causes major drag.
Seminar Report ‟05                                                 Aerodynamics In Cars

CONCLUSION

Earlier cars were poorly designed with heavy engines , protruding parts
and rectangular Shapes due to which they consumed large quantities of fuel and and
became unaffordable all theses factors lead to the development and need of
aerodynamics in the design of cars now it would be fair to say that all most all cars are
tested for getting the optimum aerodynamic configuration.
Seminar Report ‟05                                          Aerodynamics In Cars

REFERENCES

BOOKS
1) Road Vehicle Aerodynamic Design , Barnard R.H.
2) Introduction to Aerodynamics by Anderson.

WEBSITES
1) www.wikipedia.com
2) www.cardesignonline.com
Seminar Report ‟05   Aerodynamics In Cars

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