Abstract

Motivated by the Joint Urban 2003 field project and subsequent studies, magnetic resonance imaging (MRI) techniques were used to collect full-field measurements of three-dimensional fluid velocity and concentration across a scaled model of 2003 Oklahoma City. The study was intended to develop, test, and demonstrate a repeatable puff release with MRI compatible equipment. In order to accomplish this, a contaminant was injected through the floor of a city model in discrete puffs using a solenoid valve. Sealed to fit inside a water channel, the 1:2,206 scale city model covered the central business district of the city as it was in 2003. The main flow was fully turbulent with a Reynolds number of 36,000, while vertical puff injection occurred at a Reynolds number of 2,642. Using MRV and MRC methods, the three components of velocity and concentration were measured at more than 2 million locations for each of the 12 phases of the injection period. MRV measurements examined the fluid flow with respect to building geometry. Collected at heights corresponding to this MRV data, MRC measurements enabled the analysis of the vertical and lateral dispersion of the contaminant. Ultimately, the study demonstrated a novel MRI technique through contaminant puff release and can be used for the validation of urban contaminant dispersion models.

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