- In fluid dynamics, total pressure () refers to the sum of static pressure p, dynamic pressure q, and gravitational head, as expressed by Bernoulli's principle:
- where ρ is the density of the fluid, g is the local acceleration due to gravity, and z is the height above a datum.
- If the variation in height above the datum is zero, or so small it can be ignored, the above equation reduces to the following simplified form:
- Because this is the static pressure that occurs in locations where the fluid flow is entirely stopped (stagnated), this case is also called the stagnation pressure. A fluid can lose total pressure through energy dissipation. An example is the friction between the fluid and a pipe inner surface.
The dynamic pressure is calculated using the density and velocity of the fluid: