NIST FDS (Fire Dynamics Simulator)
Definition
A freely available large-eddy simulation CFD code from NIST that models coupled fire, smoke, and heat transfer in three-dimensional geometries. Validated against large experimental databases and used in forensic fire reconstruction.
- Developer
- NIST
- Model type
- Large-eddy simulation CFD code
- Simulates
- Coupled fire, smoke, and heat transfer in 3D geometry
- Cost
- Freely available
- Validation
- Tested against large experimental databases
Common questions
How does an investigator use FDS output to support a fire-origin hypothesis?+
The investigator builds a 3D model of the compartment and fuel load, runs the simulation with a proposed ignition scenario, and compares the predicted fire growth, smoke layer descent, and temperatures against physical evidence such as char patterns and witness timelines to test whether that scenario is consistent.
Can FDS results alone prove a specific cause of a fire?+
No. Simulation results test whether a hypothesised scenario is physically plausible given the observed damage and timeline, but they cannot independently establish the actual ignition source without corroborating physical and testimonial evidence.
Why does model validation against experimental databases matter for court acceptance?+
Because FDS has been benchmarked against real fire tests with known outcomes, an expert can point to that validation record to support the reliability of the modelling method itself, which is relevant to admissibility challenges under Daubert-type standards.
Related terms
- Alpert Correlation
- An expression derived by Ronald Alpert at FM Global for ceiling jet temperature and velocity as functions of heat release rate, ceiling...
- CFAST
- Consolidated Fire and Smoke Transport model from NIST; a multi-room two-zone fire model used for evacuation time analysis, detector performance prediction, and...
- Fractional Effective Dose (FED)
- A physiological model that combines exposure to CO, HCN, CO2, reduced O2, and heat into a cumulative incapacitation estimate. Used with FDS...
- Heskestad Correlation
- An analytical expression derived by Gunnar Heskestad at FM Global relating fire plume centreline temperature to heat release rate and height above...
- McCaffrey Plume Model
- A three-zone empirical model for fire plume centreline temperature and velocity developed by Brian McCaffrey at NIST, with separate power-law relationships for...
- Soot Horizon
- The visible line on vertical surfaces marking the lowest height reached by the smoke layer during the early fire growth phase, representing...
- T-Squared Fire Growth
- A model in which heat release rate increases as the square of time from established burning (HRR = alpha × t²). The...
- Two-Zone Model
- A compartment fire model that divides the room into an upper hot gas zone and a lower cool ambient zone, computing their...
- Virtual Origin
- In plume correlation models, the effective point source location below the actual fuel surface from which the plume behaves as if it...