Comparison of experiments on dense gas cloud dispersion

Abstract

A comparison is made between experimental tests and a simple entrainment model (adapted from Eidsvik, 1980 Atmospheric Environment 14, 769–777) of the dispersion of dense gas clouds in the atmospheric boundary layer. Published experimental data includes field tests of the release of isothermal dense gas samples and the spillage of liquefied natural gas as well as meteorological wind tunnel tests. The essential model characteristic, the entrainment rate, is assumed to be a simple function of the local Richardson number, which is suitable for the later stages of cloud dilution after the initial effects of release have died away. Approximate analytical expressions for the model solutions are used in correlating data with model predictions. The experimental variables considered are cloud material concentration, drift distance and drift time which are expressed in dimensionless form. While there is considerable scatter among the data, on average there is agreement with the model, especially for large Richardson number. LNG vapor clouds are found to have much greater entrainment rates than isothermal heavy gas clouds.