Features
A dedicated tool for duct acoustics with flow.
Everything a silencer engineer needs to predict attenuation and back-pressure — and nothing a general multiphysics suite makes you learn first.
SpectraSim combines three physics for silencer design in one model: frequency-domain finite-element acoustics for transmission loss, insertion loss and radiated SPL, steady or transient CFD for pressure drop and back-pressure, and wall heat transfer for gas and wall temperatures. Every licence includes every feature.
- Acoustics
- 3-D finite elements, frequency domain
- Flow
- RANS k-ω SST, OpenFOAM
- Heat
- Wall heat loss, temperature field
- Platform
- Windows 10 and 11, 64-bit, offline
- Licences
- Perpetual, yearly or monthly — all features
Modules
Which physics does SpectraSim couple?
Acoustics leads. CFD gives the pressure drop and the flow the acoustics sees; heat transfer gives the temperature that sets the speed of sound.
Acoustics
Transmission loss, insertion loss, radiated SPL and resonances by finite elements — in a medium that knows how hot the gas is.
Muffler acoustics and transmission lossFlow & pressure drop
Back-pressure, total-pressure loss and loss coefficients by CFD, with quality gates on every run.
Pressure drop and back-pressure by CFDHeat transfer
Wall heat loss and the temperature field that sets the speed of sound in the acoustics.
Wall heat loss and gas temperatureWorkflow & reports
Twelve guided wizard steps from STEP file to HTML and PDF report, with every default visible.
The guided workflow, from CAD to report Capability matrix
What does SpectraSim do, and what is the status of each feature?
Every capability of version 0.6.0a1, with its status written out. 24 are Available, 8 are Experimental and 4 are Planned.
- Available
- In the current version.
- Experimental
- Runs; results not yet verified — indications only.
- Planned
- On the roadmap, not in the current version.
| Area | Capability | Status |
|---|---|---|
| Acoustics | Frequency-domain finite-element acoustics (Helmholtz equation) in the full 3-D geometry, uniform medium | Available |
| Acoustics | Acoustic medium mapped from the CFD temperature and pressure fields (density and speed of sound at every node) | Available needs a steady compressible flow run |
| Acoustics | Ports with automatic mode selection (every propagating mode, plus evanescent modes), port sweep and superposition | Available |
| Acoustics | Transmission loss per inlet and averaged; 1/1 and 1/3 octave bands | Available |
| Acoustics | Insertion loss (power method, reference pipe built and solved automatically) with unflanged or flanged outlet terminations | Available without mean-flow convection |
| Acoustics | Radiated SPL at a microphone position, with the A-weighted overall level, from a source spectrum and the insertion loss | Available without mean-flow convection |
| Acoustics | Insertion loss with a radiation domain at the outlet (meshed half-space, valid above the outlet’s first cross-mode) | Experimental checked on a straight pipe only |
| Acoustics | Perforate transfer impedance, with grazing-flow and bias-flow options | Available |
| Acoustics | Absorbing materials as equivalent fluids: Delany–Bazley, Miki and Komatsu models, or user-defined constants | Available |
| Acoustics | JCA and JCAL absorbing-material models | Experimental checked against measured foam absorption, not yet in a full acoustic run |
| Acoustics | Mean-flow convection in the acoustic solve (transmission loss) | Experimental checked on a uniform duct only |
| Acoustics | Insertion loss and radiated SPL with mean-flow convection | Planned |
| Acoustics | Flow-generated noise (LES → Lighthill → FEM) | Planned |
| Flow | Steady RANS (k-ω SST), incompressible and compressible gas; transient option (incompressible) | Available |
| Flow | Dry air or engine exhaust gas (from fuel and excess-air ratio); inlet as normal velocity, volume or mass flow rate; outlet pressure | Available |
| Flow | Perforated plates and pipes (porous jump), absorbing packing (Darcy–Forchheimer), internal walls | Available |
| Flow | Inlet velocity given as a vector | Experimental |
| Flow | Compressible flow with the transonic solver | Experimental |
| Flow | Compressible flow with the pseudo-transient (local time-step) solver | Experimental |
| Heat transfer | Wall heat loss: conduction through the shell and any insulation, outside natural or forced convection and radiation; wall-material library; fixed-temperature or adiabatic walls | Available |
| Heat transfer | Temperature-dependent heat capacity of the gas | Experimental |
| Geometry | STEP, IGES and STL import; unit confirmation; multi-body models split into flow regions; click-to-assign faces | Available |
| Geometry | Replace the CAD in a project: settings are kept and faces are re-matched, with a review list for uncertain pairs | [MISSING M35 — confirm status] |
| Mesh | Automatic flow mesh with boundary layers, sized by curvature or from the smallest port; mesh quality check; acoustic mesh sized to the local wavelength | Available |
| Mesh | Mesh-independence study with the grid convergence index (GCI, 3 levels) | Available with curvature sizing the GCI may not be reliable |
| Studies | Run queue for unattended runs and mesh-independence studies | Available |
| Studies | Parameter sweeps, including flow-rate sweeps with the Δp–Q fit (Δp₀ = aQ² + bQ) | Experimental |
| Results | KPIs with their quality signal, convergence charts, tables, 3-D plots (wall pressure, slices, streamlines, isosurfaces, acoustic pressure) | Available |
| Results | Postprocessing: compare runs and imported measurements (txt, csv, xlsx, MATLAB .mat), with error metrics | Available |
| Reports | HTML and PDF report on demand, with title, author, logo, saved views and an optional methods appendix | Available |
| Reports | Data export: CSV, Excel, copy as TSV; charts as PNG or SVG; 3-D fields as VTK for ParaView | Available |
| Reports | Customer-branded report templates | Planned |
| Help | F1 help article for every parameter: theory, equations, default and references | Available some articles still marked Draft |
| Units | SI units throughout | Available |
| Units | SI / Imperial switch | Planned |
| Platform | Windows 10 / 11, 64-bit; runs fully offline, no telemetry | Available |
Experimental features run in the current version, but their results have not yet been checked against a real case; the program’s Help lists them under Known limitations. Planned features are not available yet and carry no dates. Measured and analytical comparisons for the Available features are on the validation page with all reference cases; the same matrix is available as machine-readable JSON.
Focus
What SpectraSim is not
We stay focused on duct, muffler and silencer products. That focus is why the workflow is short.
- Not a general multiphysics suite It is built for mufflers, silencers and ducts.
- Not a 1-D network code It solves the full 3-D geometry, cross-modes and internals included.
- Not a cloud service It runs on your workstation, offline. Models never leave your computer.
- Windows only Windows 10 and 11, 64-bit. No Linux or macOS build.
Quick answers
About SpectraSim
- What is SpectraSim?
- SpectraSim is Windows desktop software for duct acoustics with flow. From one 3-D CAD model it computes transmission loss, insertion loss and radiated SPL by finite elements, pressure drop and back-pressure by CFD, and wall heat loss.
- Which acoustic results does SpectraSim calculate?
- Transmission loss per inlet and averaged, transmission loss in 1/1 and 1/3 octave bands, insertion loss by the power method, radiated SPL with the A-weighted overall level, port powers, and the acoustic pressure on the walls at any frequency.
- Can SpectraSim calculate muffler back-pressure?
- Yes. Steady RANS k-ω SST CFD gives the total-pressure loss Δp₀ with its uncertainty, the engine back-pressure, the loss coefficient ζ and the flow split per outlet, each with its convergence and mesh quality checks.
- Which SpectraSim features are Experimental?
- The transonic and pseudo-transient compressible solvers, inlet velocity as a vector, insertion loss with a radiation domain, mean-flow convection in the acoustic solve, the JCA and JCAL material models, parameter sweeps and a temperature-dependent heat capacity. They run, but their results are not yet verified: treat them as indications.
- Which SpectraSim features are Planned?
- Insertion loss and radiated SPL with mean-flow convection, flow-generated noise (LES → Lighthill → FEM), an SI / Imperial unit switch and customer-branded report templates. Planned features are not in the current version, and no dates are published.
- Does SpectraSim need an internet connection?
- No. SpectraSim runs fully offline on Windows 10 and 11 (64-bit), with no telemetry and no online activation, so CAD models and results never leave your computer.
Model it before you build it.
Every licence includes every feature. Or let our engineers run the study for you.