Keywords: comparative modelling, dispersion modelling, passive release
Comparative modelling of a passive release from an L-shaped building using one, two and three-dimensional dispersion models
A comparative study has been made for the modelling of a passive release from an L-shaped building, in the presence of wind, using dispersion models of various complexities. Selected for the comparison were the one- and two-dimensional shallow layer models DISPLAY-1 and DISPLAY-2 and the full three-dimensional model ADREA-HF, all being part of the Dense Gas Dispersion Code Package, jointly developed by NCSR-DEMOKRITOS and JRC-ISPRA. For the shallow layer models, turbulence is modelled by means of the entrainment velocity concept, while for the three-dimensional model, a one-equation turbulence closure is used, according to which the turbulent kinetic energy conservation equation is solved. Length scales depend on the local and global flow characteristics of the L-shaped building. Concepts of volume porosity and area permeability are used. The pressure drop due to the building is taken into account by adding resistance terms in the shallow momentum equations. For model validation, the EMU-A1 wind tunnel experiment has been selected. The model results are compared against the experimental concentrations, using a statistical evaluation approach. The results clearly demonstrate the applicability of the model ADREA-HF for the present complex topography. For the shallow layer models acceptable results were obtained in CPU times much lower than ADREA-HF. Further improvements of the model for additional entrainment due to the presence of obstacles is necessary.