Fluid Dynamics (Repost)

Fluid dynamics, including mechanics of liquids and of gases, is a part of physics. We can divide the processes of any physical theory into four steps!
1. Placing observed data into general physical laws,, assuming the uniformity of nature.
2. Transferring the physical laws into mathematical form, thus obtaining a logically consistent system of axioms which usually consists of a system of differential equations.
3. Drawing conclusions from these differential equations. This is a purely mathematical step.
4. Check on the results obtained in (3) by experiments.