What this step does
Fluid flow solves the steady Reynolds-averaged (RANS) equations with the k-ω SST turbulence model, or the transient equations, with OpenFOAM (OpenFOAM user guide, 2026). The result is the mass-flow-weighted total-pressure drop between inlets and outlets. Its settings are on the Model, Material, Boundary Conditions, Solver Settings, Run Settings and Mesh steps.
Heat transfer adds the energy equation and the heat lost through the outer walls (a wall of shell and insulation layers, with outer convection and radiation). It is solved by the steady compressible solver, so it requires fluid flow and locks Analysis type to compressible; a transient heat-transfer run is not available.
Acoustics solves the Helmholtz equation for the acoustic pressure with second-order finite elements at every frequency of the sweep (Run Settings). It gives the transmission loss and, optionally, the insertion loss and the radiated sound pressure level. It can run alone (with no OpenFOAM step at all) or after the flow solution. Acoustic medium decides whether the acoustic medium is one uniform gas or is mapped from the solved flow.
The program accepts these combinations:
- at least one physics must be selected;
- heat transfer requires fluid flow and the steady compressible solver;
- the medium "From CFD fields" requires fluid flow with the steady compressible solver (it maps the solved temperature and absolute pressure).
A physics whose solver is not part of the build can be ticked and saved, but the run refuses to start and states why.
Source
The program checks these combinations whenever the case is validated. The Physics step sets the analysis type to compressible automatically when heat transfer or the mapped medium require it.
Valid range
Order of the run
With flow and acoustics, the flow is solved first, then the acoustics. With the uniform medium the acoustics does not use the flow solution, except for the perforate Mach numbers estimated from the entered flow.
Fields in this step 1
| Field | Symbol | Unit | Default |
|---|---|---|---|
| Acoustic medium | uniform |