What this step does
Convergence of a steady run. The run stops when the mean of the total-pressure drop has converged: over a window of at least Δp window iterations after the start-up and settle phases, both its linear drift and the spread of its three block means are within Δp mean-stability tolerance of the mean. Otherwise it runs to Maximum iterations.
After the run, quality gate 2 also judges:
- the initial residuals, against Residual target or the Residual drop (per equation with Per-field residual tolerances);
- the mass imbalance (0.1 % of the inlet flow);
- the wall .
A run whose pressure-drop mean converged while the residuals stayed above target is reported as "completed with warnings": the jets in a muffler often hold the residuals at to .
Transient run. The run simulates End time seconds with a time step limited by Maximum Courant number and reports the mean pressure drop of the last Averaging window; gate 2 compares it with the preceding window.
Cores. Parallel cores: 0 selects the count from the finished mesh.
Acoustics. The frequency sweep (Frequency spacing, Lowest frequency, Highest frequency, Frequency step, Number of frequencies (logarithmic), Band range), the port modes (Evanescent modes per port) and exports (Export the full scattering matrix), the mean-flow option (Mean-flow convection), the insertion loss with its reference pipe (Compute the insertion loss) and the radiated sound pressure level (Calculate radiated SPL). With flow and acoustics, a table "CFD → acoustics" shows which quantities the acoustic run takes from the flow (medium, port gas, perforate Mach numbers) and whether they are planned values or the values used. In an acoustics-only case only the acoustic panels are shown.
Source
The convergence rule and the automatic values of the residual target, the maximum iterations and the transient timing are the program's own rules; the field articles give the measurements behind them.
Valid range
Stop and continue
A steady run can be stopped or paused at any time after its start-up phase and continued later from its last saved iteration; raise the maximum iterations to continue a run that ended there.