Aeroacoustics
Aeroacoustics in OpenFOAM: finding what in the flow makes the noise
Extract acoustic sources from an unsteady flow solution — which surface, which shear layer, and at what frequency.
What it is
Turbulence radiates sound, and the sources can be computed from a time-resolved flow field. The useful output is a map rather than a decibel figure: this trailing edge, this cavity, this shear layer. That is what tells you where to change the geometry.
What the application sets up
- An unsteady run resolving the frequencies of interest, not a steady RANS
- A time step and sampling rate set from the target frequency band
- Source sampling over the run on the surfaces in question
- Spectral post-processing of the sampled data
- The compute an unsteady case needs, planned for rather than discovered
Typical uses
- Fan, blower and HVAC noise sources
- Cavity and side-mirror wind noise
- Trailing-edge noise on blades and aerofoils
- Locating which surface actually produces a tone
Industries
Sectors where this analysis is routinely asked for.
- Automotive NVH
- Fans & HVAC
- Consumer appliances
- Aerospace
What comes out
- Acoustic source maps on surfaces
- Source strength spectra
- Ranked noise-generating regions
- Before/after comparison of design changes
OpenFOAM solvers
acousticFoam
Selected and configured for you from the analysis type. You can still see every dictionary the application writes.
In every tier
This analysis type is in the free build. The free tier limits mesh size to 250,000 cells and solving to one core — not which physics you may use.
On accuracy, plainly.
Every analysis type is exercised end to end on every pass — its case is generated, meshed and run — which establishes that the setup is right, not that the answer matches your geometry. No CFD result is evidence until it is checked against something you trust: a measurement, a hand calculation, or a mesh-refinement study the application will run for you. Treat these results with the judgement you would apply to any CFD you set up yourself.