Fifteen minutes with the expansion chamber sample, then the same steps with your own STEP file. You need SpectraSim installed and a licence or trial to solve.
Open the expansion-chamber sample
Choose File → Open a sample… → Expansion chamber → Open.
The sample is a 90 mm chamber between two 30 mm pipes, set up for an acoustic transmission-loss sweep from 50 to 1500 Hz. The wizard on the left shows the steps; a tick means the step is done.
Walk through the wizard steps
- Physics — what is solved: fluid flow (pressure drop), heat transfer, acoustics.
- Geometry — the model in 3-D. Click a face to see its assignment: inlet, outlet, wall, internal wall, perforated wall.
- Material / Boundary conditions — gas, temperature, inlet flow and outlet pressure; for acoustics, the excitation.
- Numerics / Simulation control / Mesh — the defaults are chosen from the model and marked
auto; keep them for a first run.
Press F1 in any field, or click its (i), for the theory, the equations and the references behind it.
Start the run
On the Run step choose Start run. The progress bar and the convergence charts update live; Stop and Pause are next to it.
Read the results and generate a report
The Results step shows the transmission loss, the pressure drop, quality checks and 3-D plots.
- Generate report writes an HTML and a PDF report.
- Send to Postprocessing collects curves from several runs, or imported measurements, for comparison.
For an expansion chamber the transmission loss can be checked against the exact one-dimensional solution below the first cross-mode cut-on; see Validation.
Save the project
File → Save (Ctrl+S) writes one .spsim file with the settings, the CAD and the results. Open it later with File → Open, or by double-clicking it.
Set up your own model
- File → New project, and choose the physics.
- On the Geometry step load a STEP, IGES or STL file.
- Confirm its units. Always check them: CAD files do not reliably carry their unit.
- Assign the inlets, outlets and walls.
A model made of several solid bodies — pipes inside a chamber — is split into its flow regions automatically.
When something goes wrong
Help → Send feedback saves your note together with the logs in one zip; send it to support. Help → Known limitations lists what this version does not do yet and which features are still marked Experimental — the same list is in Known limitations.