This three-year award provides support for US-France cooperative research on studies of the dispersion of passive scalar contaminants from line and point sources at the wall of turbulent boundary layers. The investigators will conduct theoretical and experimental studies into the behavior and prediction of scalar fields as it relates to urban air quality. The collaboration involves research groups led by James M. Wallace of the University of Maryland and Michel Ayrault of the Fluid Mechanics and Acoustics Laboratory of the Ecole Centrale in Lyon, France. The experiments will combine optical measurement methods: Particle Image Velocimetry and Mie scattering concentration measurements in order to obtain scalar fluxes in the flows. In addition, the investigators will examine the predictive capabilities of a new non-local scalar flux model for the same flow conditions considered in the experimental work. The combined theoretical modeling and experiments will advance understanding of the behavior and prediction of scalar fields, thus reducing a principal source of uncertainty in urban air quality modeling. The US investigators bring to this collaboration expertise in studies of turbulent boundary layers and scalar dispersion. This is complemented by French expertise in PIV/Mie scattering techniques and a special windtunnel adapted to accommodate the requirements of the PIV/Mie scattering measurement techniques.
