The velocity (V) of the fluid is equal to the product of the Mach number (M) and the speed of sound (a) in that fluid. Velocity is a vector quantity that describes the rate of change of an object’s position with respect to time. It specifies both the speed of the object’s motion and its direction of movement. In simple terms, velocity tells us how fast an object is moving and in which direction it is moving. When the Mach number is less than 1 (M < 1), the fluid flow is considered subsonic, and the velocity of the fluid (V) is less than the speed of sound (a). When the Mach number is equal to 1 (M = 1), the fluid flow is at the speed of sound (a), and this condition is known as sonic or transonic flow. When the Mach number is greater than 1 (M > 1), the fluid flow is considered supersonic, and the velocity of the fluid (V) exceeds the speed of sound (a). Â
- V: Velocity of the fluid (in m/s).
- M: Mach number (dimensionless).
- a: Speed of sound in the fluid (in m/s).