Good topic. Allow me to throw some light.
Aerodynamics is an interesting area of fluid dynamics. It encompasses a lot of areas including aviation amongst other areas as you have mentioned.
The airplane wing design is an important aspect of airplane flight. Wings have streamlined cross section called airfoil. Airfoils generates lift as the angle of attack is increased until a particular angle where the lift begins to drop. This is known as the stall angle of attack. Alongside lift, drag is also generated. As the angle of attack increases the ratio of lift to drag force increases at first until an optimum value before it then decreases, signifying the dominance of drag force.
It is the aim of engineers to design the airfoil such that the optimum ratio of lift to drag is high as this enhances flight performance. High drag force is undesirable as it will require more power to propel the airplane and thus more fuel.
RE: Aerodynamics. Fundamental physical principle that explains why an airplane can stay in flight