Conservation laws

Aerodynamic problems are solved using the conservation laws, or equations derived from the conservation laws. In aerodynamics, three conservation laws are used:

• Conservation of mass: Matter is not created or destroyed. If a certain mass of fluid enters a volume, it must either exit the volume or increase the mass inside the volume.
• Conservation of momentum: Also called Newton's second law of motion
• Conservation of energy: Although it can be converted from one form to another, the total energy in a given system remains constant.

All aerodynamic problems are therefore solved by the same set of equations. However, they differ by the assumptions made in each problem. The equations become simpler as assumptions are made.

Note that these laws are based on Newtonian Mechanics, they are not applicable in Einsteinian Mechanics (the latter taking into account Einstein's theory of relativity).