Compressible flow refers to the behavior of fluids, typically gases, when their density changes significantly due to pressure or temperature variations. This phenomenon is important in various applications, such as in the design of aircraft and rocket engines, where the speed of the flow can approach or exceed the speed of sound. In compressible flow, the equations governing fluid motion, like the Navier-Stokes equations, must account for changes in density. This is different from incompressible flow, where density remains constant. Understanding compressible flow is crucial for predicting how gases behave in high-speed conditions and for optimizing performance in engineering systems.