1. Tushar Kiran Third year (Mechanical)
Aerodynamics in cars
Tushar Kiran
Third year (Mechanical)

2. Aerodynamics in Cars
Aerodynamics is itself a part of fluid dynamics, which is the study of the properties of a solid object displace a fluid such as air.
For the performance of a typical passenger car, aerodynamics is an important consideration in the achievement of maximum fuel economy, as well as in creating auto body styling that is visually appealing.

3. Terms to Know- Aerodynamics
Fluid
Mass
Aerodynamics
Drag
Lift
Rear Suction
Down Force
Frontal Area

4. Fluid
Air-
Is a type of fluid such as water that can be directed or displaced;
Has mass and is measured in terms of pressure;
Applies direct and frictional forces to objects in motion;

5. Principles One should be aware of four aerodynamic principles- Drag
Lift/Down Force
Drag Coefficient
Frontal Area

6. Drag
Drag is a combination of two forces that will work against the acceleration of your car.
Frontal Pressure occurs when tiny molecules of air hit the front of your car and is forced away to make room for other molecules to hit it.
Rear Suction occurs when an empty pocket of air is created in the back of your car resulting in a vacuum cleaner effect that tries to pull your car backward.

7. Air Flow
Rear Suction

8. Lift and Down Force
Lift is similar to rear suction in that a thin empty pocket occurs as air passes over a flat surface causing the car to lift.
Down Force is due to high pressure in curved surfaces that causes the car to be pushed down.

9. Lift and Down Force

10. Drag Coefficient
Drag Coefficient is a way of expressing how slippery a car is.
The drag coefficient (CD) is a measure of the vehicle's aerodynamic efficiency.

11. Frontal Area
Frontal Area is the total of all surfaces in the front of your vehicle which cause drag.
Area = Length x Width

12. Aerodynamic drag
Aerodynamic drag = (ρ/2) CD * A * V2, where ρ is air density, A is the projected frontal area of the body, and V is velocity.
Even though aerodynamic drag is critically dependent on the velocity, it is only the product CD times A that the designer can control.

13. Past of Aerodynamics A = frontal
area, b = wheelbase, CD = drag coefficient

14. Partition of Drag in Modern Cars
Rear View Mirrors 3 - 6% Engine Cooling 5 - 9% Underbody % Wheels, Rims and Wheel Housings 30 – 35% Vehicle Body(Shape and Sealing) %

15. Vehicle Body
Ergonomics is more and more important in new cars and for instance the height of new models is growing. Thus the accessibility is improved.

16. Wheels, Rims and Wheel Housings

17. Underbody 2 3 1

18. Engine Cooling
Mercedes-Benz 350 SL
Mercedes-Benz SL 500

19. Rear View Mirror
A CFD (Computational Fluid Dynamics) program can be very useful to optimize the shape of the rear view mirror. The pressure distribution on the side shows clearly how the rear view mirror influences the air flow on the side of the car

20. Conclusion
This short report leads actually to one major idea which is that the body of a car only contributes to roughly half of the total drag.
The major improvement for future vehicles can be reached by a smoother design of the underside.
Another important issue for drag reduction, certainly later on, will the replacement of rear view mirrors with cameras for instance.
New passenger seat configurations, like the driver seat in the front, two passenger seats in the middle and one at the rear, would make it possible to design more streamlined vehicles, paying attention to the fact that a suitable ergonomics remains.