How Does Cap's shield return back to him?

Let's assume that Captain America's super-soldier serum also came with super-physics-understanding. 

How does Cap's shield seem to fly?
The shield is formed into a discus shape for a reasoning. The discus has great aerodynamic properties and can slice through the air over long distances. It also has a high stiffness due to its shape, and due to its unique construction, it can bounce off of objects with little to no loss of angular momentum. 

How does Steve's shield return to him?
Captain America uses an innate knowledge of kinematics in order to make his shield return to him. Before he even throws it, he analyzes the angles at which his shield needs to be thrown in order to come back his direction. He even understands the difference between different kinds of collisions, as people absorb more energy than concrete, for example.