Validation of CFD-model for hydrogen dispersion

Key Findings

• FLACS-CFD validates against multiple hydrogen-dispersion experiments (jet release, garage release, vented enclosures, free jets from high-pressure vessels).
• Validation cases include the INERIS jet-release tests, GexCon garage experiments, and HySEA project benchmarks — establishing FLACS as a validated CFD code for H2 safety studies (cited 107 times per Crossref as of 2026-05).
• The paper documents the consequence-prediction accuracy of FLACS against experimental dispersion data, with concentration-decay profiles matching to within ±20 % across multiple jet-to-obstacle distances.
• FLACS resolves recirculation, building-wake and momentum-jet effects which Gauss-Plume tools (ALOHA, PHAST) cannot capture — essential for dense urban port environments where buildings, terrain and meteorology interact non-linearly.

Methods

CFD validation against published large-scale H2 dispersion experiments. The FLACS code (originally developed at Christian Michelsen Institute, now maintained by Gexcon AS / DNV) is exercised on cases with varying release geometries, pressures, and confinement conditions. Concentration-time profiles, peak concentrations, and flammable-cloud envelopes are compared between simulation and measurement.

Limitations

• Validation predates the surge in ammonia (NH3) safety applications; for NH3-specific validation see Hansen et al. follow-ups, the EMSA NH3SAFE Report 2025, and Jack Rabbit III field tests.
• Focus on hydrogen-air systems; LH2 spread/evaporation has a separate validation paper (Middha, Ichard, Arntzen 2010; DOI 10.1016/j.ijhydene.2010.03.122).
• Industrial software documentation evolves continuously — this 2009 validation establishes the baseline; ongoing validation is documented at https://www.gexcon.com/products-services/CFD-Validation/.

Relevance to Wien

Tool-Anchor-Quelle für WFK-1.4.1 (H2/NH3-Logistik Hafen Wien). Begründet, warum für innerstädtische Wien-Lagen (Donaustadt, Floridsdorf, Lobau) mit Building-Wake- und Recirculation-Effekten CFD-Modellierung (FLACS-CFD von Gexcon/DNV) eine etablierte Ergänzung über Gauss-Plume-Tools (ALOHA, PHAST, HyRam) hinaus ist. EMSA NH3SAFE Report 2025 + Yang/Lam 2024 (in WFK-1.4.1 zitiert) nutzen denselben CFD-Ansatz für Wien-vergleichbare urbane NH3-Sicherheitsfragen.

Citation

@article{middha2009flacs,
  title   = {Validation of {CFD}-model for hydrogen dispersion},
  author  = {Middha, Prankul and Hansen, Olav R. and Storvik, Idar E.},
  journal = {Journal of Loss Prevention in the Process Industries},
  volume  = {22},
  number  = {6},
  pages   = {1034--1038},
  year    = {2009},
  doi     = {10.1016/j.jlp.2009.07.020},
  publisher = {Elsevier}
}