Extension of the dense gas dispersion model DRIFT to include buoyant lift-off and buoyant rise
This report concerns the initial specification of equations extending the dense gas dispersion model DRIFT to include buoyant lift-off and rise. The lift-off modelling is based on that for a free buoyant cloud. ‘Added mass’ terms are included in the model’s vertical momentum equation since they offer the prospect of suppressing lift-off for wide clouds. The elevated continuous plume model is chosen to be similar to other published elevated plume models (eg Ott [Risø Report Risø-R-1293EN, Oct 2001], Tickle et al. [AEA Technology Report AEAT/NOIL/27328006/001(R) Issue 2, June 2001]. The elevated instantaneous model is based on the puff model of Turner [J. Fluid Mech. 19, 1964, pp481-491]. The proposed model smoothly evolves between grounded and elevated phases. Passive spreading of the elevated cloud is based on a relative diffusion model [Risø Report Risø-R-1293EN, Oct 2001]. DRIFT’s atmospheric profiles have been extended to above the surface layer and to include profiles of temperature and humidity.
This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author(s) alone and do not necessarily reflect HSE policy