A Study of Heavy Gas Effects on the Atmospheric Dispersion of Dense Gases
The atmospheric dispersion of a large, heavier-than-air gas release is affected by several physical phenomena that either do not occur or are unimportant in neutrally buoyant and trace gas releases. These include turbulence damping due to stable density stratification of the heavy gas cloud, alteration of the ambient velocity field due to gravity flow and the source momentum flux in a large release and, for cold gas releases, the effects of heat flow from the ground on cloud buoyancy and turbulence. Furthermore, the time scale of interest for a particular heavy gas release may differ considerably from the long term dose concerns associated with typical atmospheric pollutants. For example, in combustible gases releases, one is concerned with the instantaneous concentration, while in a toxic gas release one might be concerned about doses over minutes to hours. In order to make meaningful predictions of the size and duration of the hazardous concentration region from a large, heavy gas release, all of the significant physical phenomena need to be included and the appropriate concentration averaging time needs to be used.
KeywordsGravity Flow Lawrence Livermore National Laboratory Downwind Distance Vapor Cloud Stable Atmospheric Condition
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- Chan, S.T., 1983, “FEM3 — A Finite Element Model for the Simulation of Heavy Gas Dispersion and Incompressible Flow : User’s Manual”, UCRL-53397, Lawrence Livermore National Laboratory, Livermore, CA.Google Scholar
- Chan, S.T., H.C. Rodean, and D.L. Ermak, 1984a, “Numerical Simulations of Atmospheric Releases of Heavy Gases Over Variable Terrain”, Air Pollution Modeling and its Application III, Plenum Press, pp. 295 – 341.Google Scholar
- Chan, S.T., and D.L. Ermak, 1984b,”Recent Results in Simulating LNG Vapor Dispersion over Variable Terrain”, Atmospheric Dispersion of Heavy Gases and Small Particles, Spring-Verlag, pp. 105–114.Google Scholar
- Gerald, C.F., 1970, Applied Numerical Analysis, Addison-Wesley, Menlo Park, CA.Google Scholar
- Gifford, F.A., 1976, “Turbulent Diffusion — Typing Schemes : A Review”, Nuclear Safety, 17, No. 1, pp. 68–86.Google Scholar
- Morgan, D.L. Jr., L.K. Morris, and D.L. Ermak, 1983, “SLAB : A Time-Dependent Computer Model for the Dispersion of Heavy Gases Released in the Atmosphere”, UCRL-53383, Lawrence Livermore National Laboratory, Livermore, CA.Google Scholar
- Morgan, D.L. Jr., S.T. Chan, and L.K. Morris, 1984, “The Phenomenology and Modeling of Heavy Gas Dispersion”, UCRL-89460, Lawrence Livermore National Laboratory, Livermore, CA.Google Scholar
- McRae, T.G., 1985, “Analysis and Model/Data Comparisons of Large-Scale Releases of Nitrogen Tetroxide”, UCID-20388, Lawrence Livermore National Laboratory, Livermore, CA.Google Scholar