Compressible fluid flow simulations are an efficient way of solving CFD simulations where the density changes of the fluid are significant.
Density changes of gases are typically always significant therefore they are always analysed as compressible. Liquids are normally treated as incompressible as this is a more efficient way of solving these simulations, however, when a liquid has a Mach number greater than 0.3 it has to be treated as a compressible flow as the density changes become significant.
An example of a gaseous, compressible flow around an aerofoil was setup to analyse various characteristics such as the pressure, density and velocity of the air.
A Boeing HSNLF (High Speed Natural Laminar Flow) Aerofoil was modelled and setup with an airflow of 55m/s or 200km/hr which is slightly less than the take off speed of the aircraft.
Various plots were obtained from this simulation, the Velocity Plot is shown below.