There is a need for a model that can quickly describe the dispersion of materials released near buildings. Buildings produce complex flows that pose difficult challenges to dispersion modelers. This paper describes the development and testing of a new tool, the QWIC-PLUME, model that can be used to describe dispersion near buildings. The model is designed to be used with the QWIC-URB model that computes a mass consistent wind field for flows around buildings.

The QWIC-PLUME model is a Langevin equation model that describes the dispersion and transport of releases. Gradients in the wind fields are used to estimate the dissipation which is associated with the random forcing acting on particles that are transported with the instantaneous winds. The paper describes the techniques used to estimate dissipation, drift corrections, and reflection of particles. Comparisons with wind tunnel measurements and more computationally intensive model results are also described.