Fluid Dynamics is the study of how
objects in motion flow through fluids, water and air being the most prevalent of these. Also it concerns the flow of fluids in confined spaces like pipes, vents or buildings or how fluids are moved by fans or propellers. It is a broad discipline
with universal application. We and our machines are always interacting with, moving in and moving air or water. All objects move quite easily through fluids, such as a thrown ball, an automobile, someone walking, riding a bicycle, a falling object, boats, airplanes and so on. Airfoils are special streamlined objects that are designed to move much more readily through air or water than those previously listed.
There are alternative ways to explain
fluid dynamics, but the main is the one that ties air pressure to air speed claiming that fluid moves faster on one side of the airfoil than the other. The back part of the airfoil improves the flow of fluid reducing flow separation and turbulence of fluid adjacent to the surface, the boundary layer. Less separation of fluid means less energy exchange and less drag. It also allows for creating more lift. By preventing fluid from escaping from the higher pressure surface to the lower pressure surface, separation and turbulence are reduced, the pressure difference between the two sides of the airfoil is increased and there is more lift.
