Automobile Engineering | Explain the importance of an aerodynamic shape of car body.

The body of vehicle is designed to protect the passenger as well as various components of the vehicle from the air. 

An aerodynamic shape of car body is the external shape of car body which will offer least resistance to air motion. Whenever car is moving there is an air resistance to motion of car. This air resistance depends on 

(i) Size of car 

(ii) frontal shape and area 

(iii) speed and 

(iv) wind velocity. 

(v) This air resistance is given by 

Ra= Ca.A.V2

Where

 Ra= Air Resistance,

 Ca=coefficient of air resistance 

V= Velocity of vehicle (speed) 

Now as perpendicular frontal projected area of vehicle increases then vehicle air

resistance increases & vice- versa.

Figure 1. Indicates frontal area of vehicle which is vertical, flat & offers more air resistance also flat portion at the rear produces drag which pulls the vehicle back reducing the motion of the vehicle.

So frontal area of car & body of car is designed in such a way that front portion is made inclined & body is given smooth curves (using curves instead of flat surfaces). This offers a least resistance to air & called as an aerodynamic shape.  

Figure 2.indicates the use of curved surfaces in modern vehicles instead of flat surfaces .This offers less air resistance. Aerodynamic body shape of car Improves,  

● There is least air motion resistance due to the aerodynamic shape.

● Engine load is decreased and there is better fuel efficiency & average.

● Air eddies are not formed.