Modelling Tracer Dispersion from Landfills

Several wind tunnel experiments of tracer dispersionfrom reduced-scale landfill models are presented in thispaper. Different experimental set-ups, hot-wire anemometry,particle image velocimetry and tracer concentration measurementswere used for the characterisation of flow and dispersionphenomena nearby the models. The main aim of theseexperiments is to build an extensive experimental data setuseful for model validation purposes. To demonstrate thepotentiality of the experimental data set, a validation exerciseon several mathematicalmodels was performed bymeans of astatistical technique. The experiments highlighted an increasein pollutant ground level concentrations immediately downwindfrom the landfill because of induced turbulence andmean flow deflection. This phenomenon turns out to bepredominant for the dispersion process. Tests with a differentset-up showed an important dependence of the dispersionphenomena from the landfill height and highlighted howcomplex orographic conditions downwind of the landfill donot affect significantly the dispersion behaviour. Validationexercises were useful for model calibration, improving codereliability, as well as evaluating performances. The Van Uldenmodel proved to give the most encouraging results