(41x) Using Wind Tunnel Modeling based on Field Scale Experiments as a Validation Tool for Atmospheric Dispersion Models

Wind tunnel tests have long been used to study wind effects on buildings as well as consideration of air quality studies for cities. With the recognition that many important hazardous chemicals form a denser-than-air gas or aerosol cloud when released to the atmosphere, wind tunnel testing that includes buoyancy effects has become more common. Unlike field tests, wind tunnel testing can be conducted under reproducible conditions such as wind speed and direction allowing multiple tests that represents ensemble average conditions. In a series of studies, a 50:1 wind tunnel model was developed for study of the chlorine dispersion tests conducted in the Jack Rabbit II (JR-II) Mock Urban Environment (MUE). The wind tunnel tests modeled the chlorine releases using a dense gas wall jet validated by comparison of cloud arrival times using video records. Using the wind tunnel model, velocity measurements in the simulated chlorine cloud were made which were not possible in the field tests due to the corrosive nature of chlorine. The JR-II field tests are a difficult challenge to model computationally because of the interaction of the chlorine aerosol jet with the concrete pad at the point of release. The wind tunnel model approximates the chlorine cloud flow with gas flow in the wind tunnel of known velocity, density, and volumetric flow rate that approximates the field scale behavior. Because the wind tunnel test parameters are known, the wind tunnel measurements can be used for direct validation of computational model without the complications of the field scale releases. This approach of using wind tunnel modeling to complement field scale tests is planned to support the Skylark test program aimed to improve assessment of carbon dioxide pipeline hazards.