Atmospheric dispersion and individual exposure of hazardous materials. Validation and intercomparison studies

In a previous study, new approaches have been introduced in the CFD-RANS modelling, according to which the concentration time scales are estimated as a function not only of the flow turbulence time scales but also of the pollutant travel times. The new approaches have been implemented for the calculation of the concentration fluctuation dissipation time scale and the maximum individual exposure at short time intervals using the k-ζ model for turbulence parameterisation. The purpose of this study is to implement and validate again the new methodology using the widely known standard k-e model. The validation is performed using two selected trials of the MUST experiment under neutral conditions. Special emphasis is given on the selection of the constant value of the concentration fluctuation dissipation time scale when the k-e model is used. Also, an intercomparison of the results between the two turbulence models is performed with a view to identifying model strengths and limitations.