Improved Modeling of Continuous Gas Releases of Finite Duration

The consequence assessment of toxic or flammable gases released into the atmosphere is typically based on idealization of the gas source as a puff or plume, but continuous gas releases of finite duration are typically considered more realistic. Frequently, operational dispersion models are based on Gaussian concentration profiles which inherently assume symmetric concentration profiles in the along-wind direction. While this may be appropriate for very long distances, near field behavior of finite duration releases are shown to not follow this behavior in a recent experimental program. This paper discusses the wind tunnel experimental program which studied ensembles of continuous gas releases of varying duration conducted at two different wind speeds at multiple downwind distances. The data were analyzed to propose improvements in the near field modeling of finite duration releases.