Numerical study of a fire-driven flow in a narrow cavity

Research output: Contribution to journalArticle


Air cavities and gaps between material layers are common in construction systems, e.g. ventilated façades. Air cavity may provide a pathway for smoke and flame spread in case of fire. Performing physical testing to investigate different systems and fire scenarios is resource demanding. Fire Dynamics Simulator (FDS version 6.7.0) was used to simulate fire driven flow between two parallel vertical walls. Flame heights, thermal impact to the interior wall surface and upward flow velocities were predicted with FDS and compared with experimental results. The fire source was a propane burner with 8 × 391 mm2 gas outlet area. Heat release rates were 6.6 kW and 12.4 kW and the distance between the parallel walls was 40 mm. Two different convective heat transfer coefficient sub grid scale models available in FDS were investigated. In this study the cavity width to mesh cell size ratio was equal or above 10, resulting in good predictions of flame heights, upward flow velocities and wall temperatures. 2 mm grid resulted in 25% lower HRR in locations near the burner gas inlet, compared to 4 mm grid, indicating the importance of well resolved gas outlet boundary.


External organisations
  • Danish Institute of Fire and Security Technology
  • Ghent University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Civil Engineering


  • Cavity, CFD, Fire, Fire dynamics simulator FDS, Flame heights, Parallel vertical walls
Original languageEnglish
Article number102834
JournalFire Safety Journal
Publication statusPublished - 2019
Publication categoryResearch

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