Local-Scale Hazmat Dispersion Modelling for First Responders Based on High-Resolution Computational Fluid Dynamics - an Overview of CT-Analyst Hamburg

Accidental and deliberate releases of harmful substances pose a tremendous challenge to first responders because of the large number of possible casualties and the resulting potential environmental and economic damage in densely populated areas. Within minutes after a release, countermeasures must be taken to protect the population and environment adequately. This requires the exposed area, travel time of pollutants and possible exposure levels to be known in advance with sufficient accuracy in complex urban and industrial terrain where accidental releases are possible. This paper introduces an innovative and efficient concept for a more reliable local-scale hazmat dispersion modelling in the context of emergency response, developed at NRL. Using the current implementation of this approach for first response professionals in the city of Hamburg as an example, an overview of the emergency response tool CT-Analyst Hamburg is presented. Unique features of the tool such as source location reconstruction based on available measured data or the simulation of pollutant retention time in built-up terrain are discussed. The extensive efforts undertaken to carefully and reliably validate the first responder's tool are described. Both, the underlying CFD-LES simulations as well as the CT-Analyst tool have been validated extensively using high-resolution test data sets generated in special boundary layer wind tunnel facilities and available field test data.