Incompressible flowrefers to the fluid flow in which the fluid's density is constant. For a density to remain constant, the control volumehas to remain constant. Even though the pressure changes, the density will be constant for an incompressible flow. Incompressible flow means flow with variation of density due to pressure changes is negligible or infinitesimal. All the liquids at constant temperature are incompressible.Compressible flowmeans a flow that undergoes a notable variation in density with trending pressure. Densi tyr(x, y, z) is considered as a field variable for the flow dynamics. When the value of Mach number crosses above 0.3, density begins to vary and the amplitude of variation spikes when Mach number reaches and exceeds unity.The behavior of control volume (CV) for incompressible and compressible flow is depicted in the image below.

Incompressible And Compressible Flow

Incompressible flowrefers to the fluid flow in which the fluid's density is constant. For a density to remain constant, the control volumehas to remain constant. Even though the pressure changes, the density will be constant for an incompressible flow. Incompressible flow means flow with variation of density due to pressure changes is negligible or infinitesimal. All the liquids at constant temperature are incompressible.

Compressible flowmeans a flow that undergoes a notable variation in density with trending pressure. Densi tyr(x, y, z) is considered as a field variable for the flow dynamics. When the value of Mach number crosses above 0.3, density begins to vary and the amplitude of variation spikes when Mach number reaches and exceeds unity.