Basically, aerodynamics is how the air moves around objects. In a slightly more technical sense, it would be how gases move when interacting with solid bodies. The study of aerodynamics is, precisely, the study of the interaction between an object that moves and the means by which it does. The physical characteristics of the object, together with the physical characteristics of the medium, resulting in a specific dynamics of movement. That is, an acceleration, direction, and speed determined.
There are certain laws of aerodynamics, applicable to any object moving through the air, which explain the flight of objects heavier than air. For the study of the flight, it is the same to consider that the object is moving through the air as if this object is immobile and it is the air that moves (in this last way, prototypes are tested in wind tunnels of aircraft).
Aerodynamics is a branch of fluid mechanics, which is a branch of mechanics, which is a branch of physics. He specializes in studying the principles and laws that govern the interactions between air and objects. Knowing the principles of aerodynamics is useful in a long list of activities. From raising and piloting a plane, to driving a vehicle or kicking a ball. Every time we move or throw an object, a number of physical principles act that we normally do not notice.
From the above we can conclude that:
Aerodynamics is the branch of fluid mechanics that deals with the movement of air and other gaseous fluids, and the forces that act on the bodies that move in these fluids. As an example of the field of aerodynamics, we can mention the movement of an airplane through the air, the forces that the wind exerts on a structure or the operation of a windmill, among others. The presence of an object in a gaseous fluid modifies the distribution of pressures and velocities of the fluid particles, giving rise to lift and resistance forces. Modifying one of the values (pressure or velocity) automatically modifies the other in an opposite manner.
The aerodynamics, or the results of their observations, obviously apply to phenomena of everyday life. In this sense, the aerodynamics and work with the behavior of the air is very useful for phenomena such as aviation or the development of means of transport, for the construction and manufacture of cars and machines more and more powerful in space. Aerodynamics also allows us to know the movement of sound since it is transmitted through the air and this is where issues such as radio frequencies, music, sounds in general come into play. Finally, aerodynamics are equally important in construction and civil engineering activities, since elements such as buildings and bridges must take into account the presence of atmospheric masses at the time of construction.
Although aerodynamics is something that we can observe in small things, at present its main utility is in the field of aircraft and spacecraft. Today our world depends on being able to move objects, information and people quickly and efficiently. Thanks to the airplanes we have achieved it, and it is estimated that in one day there are more than 93,000 flights.
How do planes fly?
The aerodynamics can explain it to us. The basic principle by which airplanes fly is the Bernoulli principle, which holds that "the pressure exerted by a fluid is inversely proportional to its flow velocity." As the plane increases its speed, it achieves that the fluid that surrounds it (the air) exerts less pressure.
A flat object placed a little tilted up against the wind, produces lift; for example a kite. An aerodynamic profile is a body that has a specific design to take full advantage of the forces that arise from the variation of speed and pressure when this profile is placed in an air stream. A wing is an example of advanced aerodynamic profile design.
Let's see what happens when a device equipped with aerodynamic profiles (wings) moves in the air (equipped with atmospheric pressure and velocity), at a certain speed and with certain upward positioning (angle of attack), according to the laws explained.
The wing produces a flow of air in proportion to its angle of attack (the greater the angle of attack the greater the narrowing in the upper part of the wing) and the speed with which the wing moves with respect to the mass of air that surrounds it; of this air flow, the one that runs through the upper part of the profile will have a higher velocity Venturi effect than the one that runs through the lower part. That greater speed implies lower pressure (Bernoulli's theorem).
Bernoulli's theorem
The Bernoulli Theorem was formulated in 1738 by the mathematician and physicist Daniel Bernoulli and states that there is a decrease in the pressure of a fluid (liquid or gas) in motion when its speed increases. The theorem states that the total energy of a fluid system with uniform flow remains constant along the flow path. It can be shown that, as a consequence, the increase in fluid velocity must be compensated for by a decrease in its pressure.
Now, how does an airplane optimize its flight? That is, how can you increase your speed to suffer less pressure and fly more efficiently and safely? The answer is simple: thanks to an aerodynamic design.
An aerodynamic design involves surfaces that generate the least amount of friction possible. The engineers take into account every detail of the aircraft they design, every square meter of the plane has to be perfectly designed. But the real secret of why airplanes fly, are their wings. Although the Bernoulli principle is correct, the principles outlined in why an airplane flies are valid regardless of the symmetry or asymmetry of the profile and the difference in curvature between the upper and lower surfaces. If the lift depended solely on the shape of the wing, since this shape does not change with the flight, there would be no way to vary the lift; the airplane would only bear its weight at a certain speed and also be unstable and uncontrollable. We will see later how the pilot regulates the lift by controlling the angle of attack and speed. Otherwise, the Wright brothers would not have been able to fly, nor would high-speed airplanes, acrobatic planes or gliders be kept in the air.