It is well known that the Navier -- Stokes equations are one of the pillars of fluid mechanics. These equations are useful because they describe the physics of many things of academic and economic interest. They may be used to model the weather behaviour, ocean currents, water flow in a pipe and air flow around a wing. The Navier -- Stokes equations in their full and simplified forms also help with the design of train, aircraft and cars, the study of blood flow, the design of power stations and pollution analysis. This book presents contributions on the application of Navier-Stokes in some engineering applications and provides a description of how the Navier-Stokes equations can be scaled.