Trailing Vortices, swept wings, compressible flow, all terms that come to mind when thinking about Aerodynamics. The trouble is, there are so many misconceptions with regards to this topic, particularly in regard to physical explanations of the phenomenon of flight. |Its a fascinating topic, and it has applications almost everywhere. And the central piece is understand the dynamics of fluid motion. Fluids are everywhere. The air you breathe is treated as a fluid.The density of this air as you go higher is an important property for flight. Its not just this though, when we consider the flow of air past a circular body, it is noticed that there is an apparent viscous layer where the air very near the surface of the circular body stops and as to go higher - further away from the body the velocity of the air increases. Its truly fascinating!
So whether your designing the monocoque of a car, of the wing of an aircraft to the space probe that must resist the scorching heat as it reenters the atmosphere, a knowledge of aerodynamics is necessary to understand the effects of the interaction of the fluid and the body.
This field of aerodynamics still has many mysteries, especially when phenomena which have not yet been discovered appear on the scene, such as what happens when a bicycle is riding behind a truck. These phenomena can be studied so as understand what happens to flow of air when it is in such a situation.
This phenomena is known as Drafting(As seen below for race cars):