MODITIC : modelling the dispersion of toxic industrial chemicals in urban environments

The main objective of the MODITIC (Modelling the disperison of toxic industrial chemicals in urban environments) project is to enhance our fundamental understanding of the physical processes and the associated challenges regarding modelling the dispersion of non-neutral gasses in built-up environments. The project goal is to lay the ground for future improvements of dispersion models used in emergency situations by military personnel as well as civilian emergency services, thereby contributing to the improvement of emergency preparedness and response. To achieve these goals, atmospheric wind tunnel experiments have been systematically applied and novel experimental data sets for a number of carefully chosen dispersion scenarios have been provided. The same set of configurations has also been subject to computational modelling efforts using both advanced Computational Fluid Dynamics (CFD) and simpler Gaussian models. Experimental data for the release of toxic chemicals from pressurized vessels have also been made available to the project in order to provide realistic source characterisations in the case of an event. Accompanying computations using the conditions of the release experiments have been conducted in order to validate computational models and to identify their weaknesses. 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. The scientific methodology adopted in MODITIC, where numerical simulations have been conducted together with wind tunnel experiments and field trials, have proven to be very successful. This approach is recommended to be used also in future projects, including the follow-up project MODISAFE (CRN modelling of sources and agent fate).