Extended Abstract (636K)4.5
A numerical simulation of air flows over an urban area: Verification of air flows over 2-d and 3-d obstacles with wind tunnel measurements
Ted Yamada, Yamada Scince & Art Corporation, Santa Fe, NM
Considerable interest exists in understanding air flows and dispersion of airborne materials in an urban environment. Large cities are often located in coastal areas where mountains or hills are nearby. A three-dimensional atmospheric model, HOTMAC (Higher Order Turbulence Model for Atmospheric Circulation) was improved so that air flows were simulated not only in complex terrain, but also around buildings. HOTMAC was applied to model wind and turbulence distributions over a hypothetical city in coastal, complex terrain area. We nested two computational domains of fine horizontal grid spacing of 40 m and 10 m inside the outer domain where horizontal grid spacing was 160 m. It is a unique capability that a single model was able to simulate interactively mesoscale and CFD (Computational Fluid Dynamics) scale circulation. The objective of this paper was to test model results by using wind tunnel measurements. HOTMAC was used to simulate air flows over cubical and rectangular blocks in 2-d and 3-d arrangements. HOTMAC successfully reproduced blocking air flow in front of obstacles, separation at the leading edges, and recirculation zone behind obstacles. Wind profiles and reattachment distance were qualitatively in agreement with observations. However, quantitative verification was difficult because model results are sensitive to boundary conditions and wind tunnel results showed considerable variations.
Session 4, Modeling Urban Land Surfaces and Buildings: Part 1 (Room 611)
Tuesday, 13 January 2004, 11:00 AM-12:15 PM, Room 611
Previous paper