Testing of the QUIC-plume model with wind-tunnel measurements for a high-rise building
- Michael D.
- Michael J.
- David
- Balwinder
- Eric M.
There is a growing concern about the threat of a malicious release of harmful substances to the air in order to cause harm to the population. In order to help decision-makers assess the consequences of such an attack, accurate predictions of the transport and dispersion of airborne contaminants in cities are needed. The complex flows produced by buildings pose difficult challenges to dispersion modelers. Among features of concern are channeling of plumes down street channels, circular transport within street canyon vortex, upwind transport, and the retention of toxic materials trapped between buildings. Intermittent spiral vortices that develop on the downwind side of tall buildings and quickly transport material from the street surface to the top of the building are also commonplace. A number of groups have developed computational fluid dynamics that have been applied to neighborhood-scale problems and have explicitly resolved hundreds of buildings in their simulations. However, CFD models are computationally intensive and for some applications turn-around time is of the essence. For example, planning and assessment studies in which hundreds of cases must be analyzed or emergency response scenarios in which plume transport must be computed quickly. For many applications, where quick turn-around is needed (e.g., emergency response) or where many simulations must be run (e.g., vulnerability assessments), a fast response modeling system is required. Fast running models are not only needed for emergency response and post-event applications, but for scenarios in which many cases must be run or immediate feedback is needed. We have developed the QUIC (Quick Urban & Industrial Complex) dispersion modeling system to fill that need. It can relatively quickly compute the dispersion of airborne contaminants released near buildings. It is comprised of QUIC-URB, a model that computes a 3D mass consistent wind field for flows around buildings (Pardyjak and Brown, 2001), QUICPLUME, a model that describes dispersion near buildings (Williams et al., 2003), and a graphical user interface QUIC-GUI (Boswell et al., 2004). The QUIC dispersion code is currently being used for building scale to neighborhood scale transport and diffusion problems with domains on the order of several kilometers. Figure 1 illustrates the modeled dispersion for a release in downtown Salt Lake City. This paper describes the QUIC-PLUME randomwalk dispersion model formulation, the turbulence parameterization assumptions, and shows comparisons of model-computed concentration fields with measurements from a single-building wind-tunnel experiment. It is shown that the traditional three-term random walk model with a turbulence scheme based on gradients of the mean wind performs poorly for dispersion in the cavity of the single-building, and that model-experiment comparisons are improved significantly when additional drift terms are added and a non-local mixing scheme is implemented.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 977707
- Report Number(s):
- LA-UR-04-4296; TRN: US201012%%521
- Resource Relation:
- Conference: Submitted to: Fifth Conference on Urban Environment, sponsored by the American Meteorological Society and the Air&Waste Management Association, August 23-26, 2004, Vancouver, British Columbia
- Country of Publication:
- United States
- Language:
- English
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