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Fire and Smoke Propagation Modelling

CFD (Computational Fluid Dynamics)

Fire and Smoke Propagation Modelling

Numerical simulation modelling the behaviour of the structure, objects, interactions, air, gases and fire with complex material properties laws providing accurate description of the evolution of solids, liquids and gases.

Owner: Matt Ladzinski | Publication date: 2022.09.15.

Field of expertise:


Application area:

Safety Systems

Fire Engineering

Fire safety engineering is important from the viewpoint of fire prevention, life saving (smoke management, fire and smoke propagation, evacuation) and minimizing damages (fire extinction, firefighter protection).

If a building can be modelled with great accuracy and the origin, also transient fire and smoke behaviour can be described in a reliable way, we can predict different scenarios and redesign the building to resist extreme situations better.

We run a numerical simulation modelling the behaviour of the structure, objects, interactions, air, gases and fire with complex material properties laws providing accurate description of the evolution of solids, liquids and gases.

Complex Geometries

We should include the entire building and its surroundings to model better the consequences of the fire event on people and properties. Fire simulation is a complex method. It uses turbulence, chemical reactions, flame front tracking, heat flux monitoring and radiation. Moreover, it can be broadened with thermal-mechanical components.

Kings’ Cross fire accident, UK, 1987

A numerical simulation of a fire in an escalator tunnel of an underground metro station was carried out. A 1.6 MW fire emerged in a 45 m long line tunnel with inclination of almost 45°. Ansys CFD predicted the “Trench Effect” and temperature distribution. The official enquiry accepted this prediction.

Tenability of structures

Additionally, it is possible to treat the fire origin which is caused by an explosion or a major impact and the structure suffers serious damage. We use a thermo-mechanical fluid structure interaction, where the impact weakens the structure and keeps it under an intense fire for a long period of time. We can include also the deterioration of the structure in the model. This way we can identify possible evacuation routes and time before collapse.

World Trade Centre, USA, 2001

Comprehensive investigations of the collapse of the World Trade Centre have revealed the fire induced thermal states and structural failure after a thorough analysis.

Smoke propagation

We can model the effects of the geometry on smoke propagation, as well as the evolution of visibility. Usually, large areas are broken down into smaller zones with the usage of curtains and emergency smoke management systems. Sectioning helps localizing the fire and prevent life damage.

Smoke management in Complex Atria

Two scenarios were modelled in the complex structure. In the first model smoke could penetrate into many occupied areas of the building. In the second model a smoke management system that segregated the different parts of the complex, thus smoke penetrated a much smaller area.

Smoke extraction at airports

In the event of a fire at airports, an emergency smoke exhaust system will start to operate within one minute of detection. The system includes the deployment of emergency curtains, creating zones within the large indoor structure to control smoke spread.

“What-if” scenarios with virtual buildings

A virtual building allows us to investigate various disaster scenarios by the analysis of the evolution of the event with a necessary accuracy. We can also modify various structural, material and equipment properties.

We can model droplet sizes of fire suppressing systems in complex geometries to optimize the effectiveness of fire suppression equipment. Also, in case of a fire event the dispersion of pollutants can be investigated in the close area of the building with the help of simulation.

Pollutant dispersion near the River Thames, UK, case study

A fire event of a building was investigated. The simulation included other buildings within half a kilometre radius with the section of the River Thames. The model was run for a variety of prevailing winds. This way a detailed understanding of how the design would respond to different weather conditions was obtained.


Simulation is a cost-effective way to investigate numerous scenarios including extreme situations. It also provides additional information to fire engineers to take the necessary action to prevent disasters, save lives and properties.

fire and smoke propagation - complex geometry
Geometric model of the Piccadilly line tunnel with a fire at about 2/3 length of the escalator. Temperature distribution at the station a few minutes after the beginning of the fire.
tenability WTC
Truss displacement contour plot at 700 °C and temperature distribution plot of World Trade Centre analysis.
smoke management system - Atrium
Smoke penetrating many occupied areas of a building with a complex atrium (left), and same building with smoke management system that segregates the atrium (right).
smoke and fire propagation - airport
Visibility contours and smoke penetration after 15 minutes with emergency curtains in use at an airport with a fire originated in the basement level.
fire suppressing
Fire suppression droplet trajectories (left) and temperature iso surfaces with droplet trajectories before fire extinction (right).
fire and smoke propagation - pollutant, UK
Pollutant dispersion in London, UK.
smoke and fire propagation - pollutant, Budapest
Smoke spread test inside the Budapest Sports Arena (left), and iso-surfaces of 1% CO2 concentration 10 minutes after ignition. Smoke has not reached yet the upper seating area.
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