Transport und chemische Umwandlung von Luftschadstoffen im Nahbereich von Autobahnen - Numerische Simulation

On the basis of turbulence measurements near a motorway, a parametrisation of the motorway-induced turbulence was developed and integrated in the KAMM/DRAIS model system for simulation of the transport and chemical conversion of air pollutants near a motorway. There are two different mechanisms by which the motorway influences the turbulence field, i.e. vehicle-induced turbulence and turbulence production by air flow across the motorway dam, which acts as a flow obstacle. Both effects were identified in the measured turbulence field and were parametrized. The new parametrization can be verified by a comparison of measured vertical profiles of the difference in CO concentration between the windward side and the lee side of the motorway on the one hand and measured vertical concentration profiles of a tracer in a published dispersion experiment comprising model results. The full parametrization of the motorway-induced turbulence is required for a correct description of the exhaust plume height and the maximum concentration at ground level. In another section, the dispersion of coarse dust emitted on the mtorway (caused by tyre abrasion, brake liner abrasion, road surface, resuspension) is simulated. The simulated concentration distributions on the lee side of the motorway suggest a strong influence of motorway-induced turbulence. The range of particle dispersion depends largely on their diameter. Large-diameter particles (100 #mu#m) are dispersed over several meters while small particles (1#mu#m) behave like an inert gas. The characteristic measured size distributions of th coarse dust can be explained by the model calculations.SIGLEAvailable from TIB Hannover: RN 8424(32) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman