The ratio of static pressure () to freestream pressure (), often denoted as , is a dimensionless parameter used in fluid dynamics and aerodynamics to describe the pressure variation at a specific point in a fluid flow relative to the freestream pressure. The ratio provides information about how the local pressure compares to the freestream pressure. It is used to quantify pressure deviations or fluctuations in the flow field.
- Ratio of static to the freestream pressure (p/p∞)
- Ratio of static to the freestream temperature (T/T∞)
- Specific heat ratio (γ)