A comparison of small scale laboratory experiments with the environmental protection agency recommended dense gas dispersion models: An assessment of the validity of salt bath modeling of atmospheric flows

Accurate dense gas dispersion modeling is important in a number of fields from modeling smoke movement in a room to the spreading of dense toxic gas releases such as resulted from the Chlorine spill in Graniteville, SC in 2005. To this end, a series of small scale laboratory experiments using instantaneous releases of a cylindrical, finite volume of dense salt water were performed. In the experiments, the horizontal spread of the dense liquid over a flat surface (i.e. gravity current front position over time) was measured.;The results of these small scale experiments were compared to two dense gas dispersion models (DEGADIS and SLAB) for large releases of dense gas in low wind scenarios. The goal of this work is to see if the small scale laboratory experiments can be used to model large scale buoyancy driven flows. The dense gas release models were also compared to each other to see if their results were similar. Data from both the small scale lab experiments and the large scale models were also compared to previously published experimental data.;The raw experimental data was non-dimensionalised with front position scaled on the initial cylinder radius and time scaled on H/g' where H is the cylinder height and g' is the reduced gravity of the salt water. This scaling approach collapsed the data onto a series of curves each representing a different cylinder aspect ratio. To account for the dependence of the spreading rate on the aspect ratio, a scaling scheme developed by Huq (1996) was adopted. This scaling resulted in approximate collapse of all the experimental data onto a single curve. The data also agreed well with the experimental data of Huq (measured using a sector tank) as well as the simulation data from DEGADIS, however, the SLAB simulation data followed a completely different curve.