Gravity Spreading in the Dispersion of Dense Gas Plumes
Conference
·
OSTI ID:6061903
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
The atmospheric dispersion of a denser-than-air release is affected by several physical phenomena that either do not occur or are unimportant in a trace gas release. The main phenomena are directly related to the density structure of the dense gas cloud. They are damping of the turbulence level due to stable density stratification within the cloud and alteration of the ambient velocity field due to gravity flow resulting from horizontal gradients in the cloud density. In this paper we address the phenomena of gravity spreading of a denser-than-air cloud dispersing over flat terrain. Specifically, we attempt to interpret the gravity spreading results observed in wind-tunnel studies1 conducted by CPP Inc. These experiments involved dense gas dispersion under conditions of large surface roughness where the height of the surface roughness elements was comparable to the height of the dispersing dense gas cloud. The gravity spreading results were investigated by Roberts et al. who found a transition in the dependence of the gravity flow velocity on the hydrostatic pressure head within the dense gas cloud. Near the source, the gravity flow velocity followed the well-known square root dependence; however, at larger downwind distances, the dependence appeared to become linear. They interpret this transition using arguments proposed by Linden and Simpson3-4 to describe the gravity flow rates observed in their lock-exchange experiments, but do not develop criteria for the onset of transition.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6061903
- Report Number(s):
- UCRL-JC--105011; CONF-910530--1; ON: DE91010155; CNN: MIPR N90-29
- Country of Publication:
- United States
- Language:
- English
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