This is a visualisation of a dense gas release in Champs-Élysée, Paris, made by FFI.
It is a European Defence Agency (EDA) project led by Norway (FFI) with participants from Sweden (FOI), France (DGA and INERIS), and United Kingdom (University of Surrey). The project started 01.09.2012 and ended 29.02.2016.
The main objective of MODITIC was to enhance our fundamental understanding of modelling the dispersion of heavier-than-air gasses in built-up environments. The project goal was to lay the ground for future improvements of dispersion models used in emergency situations by military personnel as well as civilian emergency services, thereby improving emergency preparedness and response.
The project work encompasses atmospheric wind tunnel experiments on neutral and dense gas dispersion for a selection of geometries with increasing complexity. Selected geometries were subject to computational modelling efforts using both advanced Computational Fluid Dynamics (CFD) and simpler Gaussian models to investigate performance of various numerical methods. In addition, special data sets were compiled to examine inverse modelling capabilities. The project also made use of available experimental data for outdoor and indoor ammonia releases from pressurized vessels in order to test modelling strategies to realistically characterise the release characteristics.
The project has generated a large database comprising experimental and numerical results for release and dispersion of neutral and dense gasses in configurations ranging from simple to complex geometries. This database will be a valuable addition to the body of reference data needed to advance the fundamental understanding of dispersion in urban environments and its modelling. The database may be used for development, improvement and validation of dispersion models for hazardous materials in urban environments.