Chemical Reactions: Explosion and Pollutant Dispersion of Oil Storage Tank

This project simulates the explosion of oil storage tanks and the subsequent dispersion of combustion pollutants across an urban area using ANSYS Fluent. The core of the analysis lies in modelling reacting flow: an explosion is fundamentally a rapid, energetic chemical reaction that consumes fuel and releases heat together with a range of gaseous products, and capturing that behaviour requires a flow model capable of tracking multiple chemical species and their transport through the surrounding air.

The motivation is a real safety concern. In regions that host oil reservoirs, the tanks represent a persistent explosion hazard, and a single event can release large quantities of pollutants such as carbon dioxide and other combustion gases into the atmosphere. Where residential neighbourhoods and industrial units sit close to the tank farm, the way these pollutants spread and reach the surrounding population becomes a critical question for risk assessment and emergency planning. This simulation is built to answer exactly that question.

The geometry is a three-dimensional urban domain measuring 6.6 km in length, 4.6 km in width and 200 m in height, created in Design Modeler. Within it, a dedicated zone contains eighteen cylindrical oil tanks, while several further zones represent residential and industrial districts. The domain is discretised with an unstructured mesh of 1,746,979 elements.

Because the explosion involves extensive chemical reactions among several gaseous constituents, the Species Transport model forms the heart of the setup. Seven species are modelled — CO₂, SO₂, NO₂, CO, H₂O, C and air — with air acting as the background fluid throughout the domain. The effect of the explosion is introduced within the tank region through defined energy and mass sources: a heat source of 139,072.7 W/m together with production rates for each pollutant (for example, CO₂ at 0.1358 kg/m³·s, H₂O at 0.0679 kg/m³·s, CO at 0.0047 kg/m³·s, SO₂ at 0.000131 kg/m³·s, C at 0.0068 kg/m³·s and a very small NO₂ contribution). This source-based representation lets the model release the heat and combustion products of the explosion directly into the reacting-flow field.

Wind is the primary driver of dispersion. The northern and western faces of the domain are set as airflow inlets and the eastern and southern faces as outlets. Open airflow enters at 300 K and 20 m/s, directed at 60° (with x- and y-velocity components of 20·cos60° and 20·sin60° respectively), so that wind speed and direction govern how far and in which direction the pollutant plume travels across the city.

The solution yields three-dimensional contours of temperature and of the volume fraction of each gaseous species throughout the domain. The results demonstrate that, in the event of such an explosion, the released pollutants are carried into the surrounding residential and industrial zones, confirming the potential exposure of the urban population. As a study in chemical-reaction flow modelling, the project shows how species transport combined with defined energy and mass sources can reproduce the generation and atmospheric spread of combustion products — a powerful basis for evaluating explosion hazards and informing the siting, spacing and protection of facilities near populated areas.