twodee: the Health and Safety Laboratory's shallow layer model for heavy gas dispersion Part 3: Experimental validation (Thorney Island)

• Published in: Journal of hazardous materials 1999-05, Vol.66 (3), p.239-261
• Main Authors: Hankin, R.K.S., Britter, R.E.
• Format: Article
• Language: English
• Subjects: Accident prevention; Air Pollutants, Occupational - analysis; Air Pollutants, Occupational - pharmacokinetics; Algorithms; Altitude; Applied sciences; Atmospheric pollution; Bias; Convection, turbulence, diffusion. Boundary layer structure and dynamics; Diffusion; Earth, ocean, space; Environmental Monitoring - methods; Exact sciences and technology; External geophysics; Gases - analysis; Gases - pharmacokinetics; Health risks; Heavy gas dispersion; Humans; Mathematical models; Meteorology; Models, Molecular; Numerical Analysis, Computer-Assisted; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Predictive Value of Tests; Reproducibility of Results; Rheology; Risk assessment; Sensitivity and Specificity; Thorney Island; Toxic materials; twodee; Wind
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/S0304-3894(98)00270-2

Part 1 of this three-part paper described the mathematical and physical basis of twodee, the Health and Safety Laboratory's shallow layer model for heavy gas dispersion. In part 2, the numerical solution method used to simulate the twodee mathematical model was developed; the flux correction scheme of Zalesak [S.T. Zalesak, Fully multidimensional flux-corrected transport algorithms for fluids, Journal of Computational Physics, 31 (1979) 335–362.] was used in twodee. This paper compares results of the twodee model to the experimental results taken at Thorney Island [J. McQuaid, B. Roebuck, The dispersion of heavier-than-air gas from a fenced enclosure. Final report to the U.S. Coast Guard on contract with the Health and Safety Executive. Technical Report RPG 1185, Safety Engineering Laboratory, Research and Laboratory Services Division, Broad Lane, Sheffield S3 7HQ, UK, 1985.]. There is no evidence to suggest that twodee predictions could be improved by changing any of the entrainment parameters from generally accepted values [R.K.S. Hankin, Heavy gas dispersion over complex terrain, PhD thesis, Cambridge University, 1997.]. The twodee model was broadly insensitive to the exact values of the entrainment parameters.