compressible fluid flow

Compressible fluid flow refers to the movement of fluids, such as gases, where changes in pressure cause significant variations in density. This is in contrast to incompressible flow, an approximation often used for liquids and gases at low speeds, where density is assumed to be constant.12

The behavior of compressible fluids is often analyzed using the Mach number, which is the ratio of the fluid's velocity to the speed of sound within that fluid. When the Mach number is less than approximately 0.3, the fluid can often be treated as incompressible. However, as the Mach number increases, especially above 1, the fluid's compressibility becomes a critical factor, leading to phenomena like shock waves due to the compression of the surrounding fluid. The study of compressible flow is essential in fields like aerodynamics and gas dynamics.2