A comparison with experimental data of several models for dispersion of heavy vapor clouds

• Published in: Journal of hazardous materials 1982-07, Vol.6 (1-2), p.161-180
• Main Authors: Woodward, J.L., Havens, J.A., Mcbride, W.C., Taft, J.R.
• Format: Article
• Language: English
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/0304-3894(82)80038-1

A comparison is reported between experimental data obtained from spills of heavy gas or volatile liquids and predictions of five different models of heavy vapor cloud dispersion. The models chosen for comparison and their sources are: MARIAH (Deygon-Ra, Inc.), ZEPHYR (Energy Resources Co., Inc.), HEGADAS-II (Shell), Eidsvik's “top hat” model (Norwegian Institute for Air Research), and the Germeles and Drake “top hat” model (Cabot Corp.). They are compared with the experimental LNG spills by Esso Research and Engineering Co. on water at Matagorda Bay, Texas (specifically Esso Runs 11, 16, 17) and the releases of heavy gas at Porton Down, Gt. Britain, sponsored by the Health and Safety Executive (specifically HSE Trials 6, 8, 20). It was found that the eddy diffusivity (K-theory) type of models, MARIAH and ZEPHYR, were best able to fit the HSE Porton Down data (for both near and far, high and low sensors). The HEGADAS-II model predictions best fit Esso Runs 11 and 17. However, HEGADAS-II cannot describe the calm wind cases, Esso Run 16 and HSE Trial 8. The Eidsvik model is recommended as one of the most advanced of the “top hat” class of models. It generally matches well the HSE Porton Down data for which it was calibrated. However, both HEGADAS-II and Eidsvik's model poorly fit sensor responses close to the source in the HSE trials; more distant sensors are matched better. The Germeles and Drake model seriously overpredicts air entrainment for HSE Trial 8, and overpredicts cloud dimensions for Esso Run 16. It reverts to the neutrally buoyant Gaussian form for four of the six experiments considered.