Theory
OpenFOAM writes the full fields (velocity, pressure, turbulence) at every multiple of this interval (writeControl adjustableRunTime) (OpenFOAM user guide, 2026). The pressure-drop monitors are written at every time step regardless, so the reported average does not depend on this setting. The saved fields are what the result plots, the report's pictures and a restart use.
On auto, equation (1), at least 20 saved solutions fall inside the averaging window. Each saved solution takes disk space comparable to the mesh itself.
Equations
| where | meaning | unit |
|---|---|---|
| Save interval (auto) | s | |
| Averaging window (resolved, auto or typed) | s |
Default and rule
- Default
- auto: averaging window / 20Computed by the program
- Rule
Auto: . With the provisional averaging window of 0.1 s this is 0.005 s.
- Source
This is the program's rule: 20 samples per window match the resolution for which the steady averaging window was designed.
Valid range > 0; a warning when coarser than averaging window / 20
Values
Above 0. A typed interval coarser than triggers a warning (fewer than 20 saved solutions in the window).