Wind tunnel evaluation of a vehicle pollution dispersion model

A wind tunnel study of pollution dispersion in the wake of a moving vehicle in a cross-wind has been performed in which a 1/50th scale lorry was fired across an environmental wind tunnel with a simulated boundary layer. A flame ionization detector was positioned at various distances downwind of the model to measure the propane which was emitted by the lorry. Individual time series of propane concentration and ensemble averages thereof provided extensive information about the nature of wake-wind interaction and it effects on the dispersion process. Results from both a rural roadway and an urban street canyon are presented. The results were used to assess the validity of a numerical model, PUFFER (Hargreaves and Baker, J. Wind Eng. Ind. Aerodyn. 69–71 (1997) 927). It was found that the model performed best when employing an auto-regressive moving average (ARMA)-generated wind time series as input. Ensemble averages of several model runs, each started with a differently seeded ARMA model, showed encouraging agreement with the experimental ensemble averages.