Recorded presentation2.1
Particle dispersion in an urban environment
Mario F. Trujillo, Applied Research Lab, State College, PA; and A. E. Parkhill and S. E. Haupt
Besides the gaseous emissions that are typically released from an explosion or other violent source, a cloud of particles is likely to be present as well. Their dynamics, however, are not generally governed by passive scalar advection leading to distinct characteristics. The analysis for inertial particles is extended from canonical flows, where the particle preferential spatial concentration is well established in the literature, to a much larger scale consisting of a prototypical urban configuration. A Large-Eddy simulation approach is used to solve the fluid dynamics coupled to a Lagrangian treatment for particle dynamics. Low mass loadings are considered leading to a one-way momentum coupled formulation for the particle-fluid system. The dispersion characteristics are analyzed in terms of the ratio of particle time constant to flow time scale (Stokes). It is observed that for low values of Stokes the dispersion metrics in terms of particle dispersion variance and dispersion coefficient approach the values corresponding to a passive scalar. The maximum deviation from passive scalar behavior is observed in regions of high vorticity, particularly near the flow separation zones. Models for incorporating subgrid-scale turbulent forcing on the inertial particle-fluid are suggested. Recorded presentation
Session 2, AIR QUALITY MODELING AND FORECASTING-II
Monday, 21 January 2008, 10:45 AM-11:45 AM, 220
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