The Ma represents the Mach number
The Ma represents the Mach number, V is the velocity of flow, and a is the speed of sound at sea level. It was found online that the value for the speed of sound at sea level was 340.29ms. When the Mach number is lower than 0.3, it is acceptable to assume incompressibility. On the other hand, the change in density cannot be neglected because the density must be considered as a significant parameter. For example, if the velocity of a car is higher than 100ms, the suitable approach to conduct credible numerical analysis is the compressible flow. Aside from the velocity, the effect of thermal properties on the density changes has to be taken into consideration for geophysical flows 3.