Theory
The program uses the value directly as . It is the reference of every gauge pressure of the case, the pressure at which the gas density is evaluated, and the operating pressure of the compressible solver (see Ambient pressure: mode).
Enter the measured barometric pressure of a test, or the pressure in a test cell, when it is known. For a standard day at a given altitude, use altitude mode instead.
Equations
| where | meaning | unit |
|---|---|---|
| Gas density at the ambient pressure | kg/m³ | |
| Atmospheric pressure (this setting) | Pa | |
| Molar mass of the gas | kg/kmol | |
| Universal gas constant, 8314.47 | J/(kmol K) | |
| Material temperature | K |
Default and rule
- Default
- 101 325 Pa (used only in pressure mode)
- Rule
101 325 Pa when switching to pressure mode for the first time; a saved value is kept.
- Source
The program uses the typed value directly as the ambient pressure; the density follows from the ideal-gas law, equation (1).
Valid range 40 000 to 110 000 Pa absolute
Values
40 000 to 110 000 Pa, absolute (not gauge). Pressure mode requires a value.
Absolute, not gauge
Typing a gauge pressure (for example 0 or a few hundred Pa) is refused by the range; the field is the full atmospheric pressure.