The science of how air moves around and inside objects is known as aerodynamics. Because air is a very thin sort of fluid, it might be referred to as “Fluid Dynamics.” Above a certain speed, the airflow around and through a vehicle has a greater impact on acceleration, top speed, fuel economy, and handling.
As a result, to design the finest automobile feasible, we must first comprehend and maximize how air flows around and through the body, its apertures, and aerodynamic devices.
Principles of Aerodynamics
Driving an automobile through the air requires energy, no matter how slowly it travels, and this energy is needed to overcome the drag force.
In-vehicle aerodynamics, drag is essentially composed of three forces:
- The action of a vehicle’s body pushing air out of the path is known as frontal pressure.
- The result of air being unable to fill the space left by the car body is known as the rear vacuum.
- The impact of friction caused by slow-moving air at the surface of the vehicle body is known as the boundary layer.
- We can characterize most airflow interactions with a vehicle body using these three forces.
As seen in diagram D1 below, frontal pressure is created by air seeking to flow around the front of the vehicle.
Frontal Pressure (Figure D1) is a type of drag in which the vehicle must push air molecules out of the way as it goes through the air.
Figure D1. Frontal pressure is a type of drag that occurs when a vehicle drives through the air and has to push air molecules out of the way.
As millions of air molecules approach the car’s front end, they begin to compress, raising the air pressure in front of it. At the same time, the air molecules traveling along the car’s sides are at atmospheric pressure, which is lower than the pressure experienced by the molecules at the front.
Suppose the valve to the lower pressure environment outside the tank is opened. In that case, air molecules will naturally flow to the lower pressure region, gradually equalizing the pressure within and outside the tank, just as they would in an air tank. Any vehicle is subject to the same rules. As shown in diagram D1, compressed air molecules naturally seek a path out of the high-pressure zone in front of the car, and they find it around the sides, top, and bottom of the vehicle.
Vacuum in the Back
The “hole” left in the air when a car passes through causes a rear vacuum. Please look at our demonstration automobile in diagram D2 below to see how this works. The car’s blocky sedan body creates a hole in the air as it travels along a road. As previously said, air rushes about the body.
The space immediately behind the car’s back window and the trunk is “empty” or like a vacuum at speeds above a crawl. The air molecules cannot fill the hole as rapidly as the automobile can produce it, resulting in these vacant regions. The air molecules try to fill in this space, but the car is constantly one step ahead, resulting in a constant vacuum sucking in the opposite direction.