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An open-source alternative to Flowmaster, AFT Fathom, or GT-SUITE for preliminary design ​

Commercial 1-D system-simulation tools cover much of the same ground as OpenFLUME: pipe networks, pressure drop and flow distribution, thermal coupling, and transients. Examples include Simcenter Flowmaster (Siemens), AFT Fathom and AFT Arrow (Applied Flow Technology), GT-SUITE (Gamma Technologies), EcosimPro, Simscape Fluids (MathWorks), and Modelica-based environments.

OpenFLUME does not replace these tools in general. It is Alpha software from a single author, its component library is much smaller, and it has no industrial qualification history. It is useful for preliminary sizing, teaching, and analysis that has to be auditable end to end.

What the commercial tools generally offer ​

These are general, publicly known characteristics; check each vendor for current features, licensing, and pricing.

  • Licensed, installed desktop applications (or toolboxes inside a host platform such as MATLAB/Simulink for Simscape Fluids). Modelica is an open modeling language; OpenModelica is an open-source environment, and commercial Modelica tools also exist.
  • Large, sector-specific component libraries built up over many years, often with vendor-maintained loss and performance data.
  • A record of industrial use in each tool's target sectors, plus vendor documentation, training, and commercial support.
  • Capabilities OpenFLUME lacks, varying by product: for example dedicated surge and waterhammer analysis, compressor and turbine maps, wider two-phase modeling, co-simulation interfaces, and integration with other engineering tools.

What OpenFLUME offers instead ​

  • Zero install. The app runs in a browser. No account, license server, or IT ticket.
  • Local-first. The solver runs in a Web Worker on your machine and model data is not uploaded.
  • Open source, MIT licensed. The equations, closures, tolerances, and tests are public, so a reviewer can trace any result to the code that produced it.
  • Published verification. Seven reports are generated from live solves by scripts in the repository, and their gate tests run in CI.
  • Scriptable. pip install openflume drives the same core from Python, and models are plain-text .fn files that diff cleanly in version control.

Where OpenFLUME fits ​

Reasonable uses:

  • Preliminary and conceptual sizing. First-pass line sizes, orifice and venturi areas, tank blowdown times, pressurant budgets, heat-exchanger segment counts, and rough chilldown trends, before a model is built in the tool of record.
  • Independent cross-checks. A second solver with a different code base can check a result from your primary tool, especially when the case reduces to one of the verified problem types.
  • Teaching. Students open a model from a link and run it in the browser. The verification reports show the closed-form solutions next to the computed ones.
  • Auditable analysis. Open source, a config hash on every run, and stale-result marking (§8.7) give a reviewer every assumption behind a result.
  • Scripted studies. Parameter sweeps and optimizer loops from Python.

Poor fits (use a qualified commercial tool or a specialist code):

  • Water hammer and fast valve transients governed by acoustic wave timing. OpenFLUME has lumped inertia only, with no method of characteristics.
  • Compressor or turbine systems. Turbomachinery is a pump curve only, with no shaft-work heating.
  • Shocks, over-expanded nozzles, or supersonic-to-subsonic transitions.
  • High-void-fraction two-phase pressure drop. OpenFLUME uses HEM only, which under-predicts it.
  • Cavitation risk on pumps and valves. Cavitation is modeled only at the cavitating-venturi closure.
  • Mixing of unlike fluids at junctions, outside CEA reacting junctions.
  • Results of record for design reviews, certification, or safety cases, where your organization requires a qualified, supported tool.
  • Large libraries of vendor-specific components (valves, fittings, HVAC, automotive, process plant). OpenFLUME has 19 branch types, plus user JavaScript components you would have to write and validate yourself.

The full list of structural limits is §1.7 Scope Boundaries.

Using OpenFLUME alongside commercial tools ​

  1. Start from a verified case. Open the nearest built-in example or report case and confirm it matches before extending it. Sanity: orifice hand-calc converges to a closed form you can check by hand.
  2. Check against hand calculations. The incompressible solver reproduces its closed-form references to the Newton tolerance (hydraulics report). If your model disagrees with a hand calculation, find out why.
  3. Refine the discretization. Spatial resolution is up to you (§1.2). Refine until the answer you care about stops changing.
  4. Check correlation status. Some closures are marked research status (§8.5).
  5. Carry results forward into the tool of record when the decision matters.

If OpenFLUME and a commercial tool disagree on a case where you trust the reference, open an issue with the reference value, tolerance, units, and the .fn file.

See also the comparison overview, NASA GFSSP, and SINDA/FLUINT.