[granzer]

I have recently started studying solution methods for compressible and incompressible flows. From what I understand compressible flows are high Mach number flows and incompressible flows are low Mach number flow. Compressible and incompressible are the property of the flow and not of the fluid. For compressible flow, we have a relationship between density pressure via an equation of state.
a) What about flow through a centrifugal gas compressor or during combustion constant pressure)? Both these cases density is changing but the Mach number is low? Should I use compressible flow solver even though the Mach number is very low? According to https://knowledge.autodesk.com/suppo...5B008-htm.html it is not compressible flow.
b) Does the equation of state hold only for high mach number flows or does it hold even for low Mach number flows but with changes in density (like the examples above) ?