The Seveso III Directive (implemented through the COMAH 2015 regulations in the UK) is the main legislation dealing with the control of on-shore majoraccident hazards. Among other duties, it requires a detailed risk assessment. The regulatory framework surrounding the Seveso Directive requires that major accident hazards are identified and assessed to evaluate their potential impact on the safety of people and the environment. As such, predictive modelling forms an essential part of compliance.

The predictive models that are used directly influence the output and hence can directly impact safety. It is therefore important that the range of applicability and limitations of such models is well understood so they can be applied correctly.

The use of Computational Fluid Dynamics (CFD) is becoming more and more common in the assessment of events associated with the potential release of hazardous materials. With the continuous development and improvement in CFD algorithms, availability and cost of high-performance computing facilities, the use of CFD is becoming even more relevant for use in safety engineering. As such, attention has turned to the use of CFD to meet the regulatory requirements associated with Seveso III, particularly in scenarios with certain complexities that phenomenological models cannot accurately account for.