The study consist, as its name says, in the resolution of the Navier-Stokes equations applied to solving concrete engineering cases. Going into more detail, this study is divided in three basic parts. The first consist in the explanation of the involved theory that is behind the implementation of a code that solves a CFD&HT problem, as well as the numerical methods and the physics involved. In the second part of the study, is where is entered in detail on the resolution of four concrete cases. Those four practical cases have been develop in order to learn and accomplish the knowledge needed to be able to solve cases more closer to the real engineering applications. And at the same time, to verify that the implemented codes are correct, while comparing the obtained result with the benchmark ones. Finally, in the third part is entered in the detail of solving a concrete case of a propriety engineering application. This case consists in studying the air conditioning behaviour of a room (HVAC&R), through programing the code and analysing the obtained results.