Compressible refers to a material or substance that can be reduced in volume when a force is applied to it. Compressible materials are usually gases or liquids, but can also be solids under certain conditions.
Compressible flow is a type of fluid flow in which the density of the fluid changes significantly due to changes in pressure. This type of flow is typically encountered in high-speed flows, such as those found in aircraft engines, rocket engines, and supersonic wind tunnels. Compressible flow is characterized by a decrease in density as the pressure increases, and an increase in density as the pressure decreases.
In compressible flow, the speed of sound is an important factor. The speed of sound is the speed at which a pressure wave propagates through a medium. In a compressible flow, the speed of sound is dependent on the temperature and pressure of the medium. As the pressure increases, the speed of sound increases, and as the pressure decreases, the speed of sound decreases.
The Mach number is a dimensionless number that is used to describe the speed of a compressible flow relative to the speed of sound. The Mach number is equal to the ratio of the flow speed to the speed of sound. When the Mach number is greater than one, the flow is said to be supersonic, and when the Mach number is less than one, the flow is said to be subsonic.
Compressible flow is also characterized by the presence of shock waves. Shock waves are regions of high pressure and temperature that form when a supersonic flow encounters an obstacle. Shock waves can cause significant changes in the flow properties, such as pressure, temperature, and velocity.
Compressible flow is an important concept in the study of fluid dynamics. It is used to describe the behavior of high-speed flows, such as those found in aircraft engines and supersonic wind tunnels. The Mach number and shock waves are important concepts in the study of compressible flow.