Symposium on Planning, Nowcasting, and Forecasting in the Urban Zone


Improved Velocity Deficit Parameterizations for a Fast Response Urban Wind Model

Eric R. Pardyjak, University of Utah, Salt Lake City, UT; and M. J. Brown and N. Bagal

The QUIC (Quick Urban & Industrial Complex) dispersion modeling system has been developed to provide high-resolution wind and concentration fields in cities. The fast response 3D urban wind model QUIC-URB explicitly solves for the flow field around buildings using a suite of empirical parameterizations and mass conservation. Previous evaluations of the model against single and multiple building wind tunnel data sets have shown weaknesses in several of the standard parameterizations. One such weakness is the parameterization for the far wake velocity deficit region. Since conservation of mass does not provide a mechanism to produce diffusion, the far wake parameterization must include such physics. The standard QUIC-URB parameterization contains an ellipsoidal envelope for the velocity deficit region that is confined to the width of the building. As a result, mean velocity gradients associated with turbulent production are excessively strong and confined to narrow region. For this work, a shelter model with a Gaussian shaped envelope that extends beyond the width of the building has been implemented and compared to single building wind tunnel results. The shelter model significantly improves the prediction of velocity distributions in the far wake.

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Session 7, Modeling Urban Land Surfaces and Buildings: Part 2 (Room 611)
Wednesday, 14 January 2004, 8:30 AM-9:30 AM, Room 611

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