What is Compressible and Incompressible flow??
COMPRESSIBLEAND INCOMPRESSIBLE FLOW
All fluids are compressible, so that their density will change with pressure, but,under steady flow conditions and provided that the changes of density are small, itis often possible to simplify the analysis of a problem by assuming that the fluid isincompressible and of constant density.Liquids are relatively difficult to compress, it is usual to treat them as if they wereincompressible for all cases of steady flow. However, in unsteady flow conditions,high pressure differences can develop and the compressibility of liquids must betaken into account.
Gases are easily compressed and, except when changes of pressure and, therefore,density are very small, the effects of compressibility and changes of internalenergy must be taken into account.