The speed of sound refers to the velocity at which sound waves propagate through a medium. It is the rate at which small pressure disturbances, or sound waves, travel through the substance. The speed of sound varies depending on the properties of the medium, such as its temperature and density.
- a∞ is the speed of sound in the fluid (at the freestream conditions)
- γ is the specific heat ratio (also known as the adiabatic index or heat capacity ratio) of the fluid
- R is the specific gas constant for the fluid
- T∞ is the temperature of the freestream flow in Kelvin