The representation of dynamic flow effects in a Lagrangian puff dispersion model

A technique for incorporating buoyancy-driven dynamics in a Lagrangian puff model is described. The dynamic effects are non-linear and therefore proper treatment requires interaction integrals for overlapping puffs. Conservation laws for the volume integral of momentum and buoyancy over an individual puff are based on the fundamental equations of motion. A simplified representation of the field of motion associated with the buoyancy-driven dynamics is then used to move and distort the puffs. The effects associated with dense gas 'slumping' on the ground are represented by lateral divergence of the velocity field, with a magnitude based on conservation of the moment of vorticity. The model predictions are compared with a number of experimental results on buoyant plume rise and dense gas dispersion. (C) 1999 Elsevier Science B.V. All rights reserved.