A puff-particle dispersion model

A meso-scale puff diffusion model is presented which makes use of the concept of relative diffusion to disperse the puffs and moves their centres of mass by incorporating a Lagrangian stochastic dispersion model as it is normally used to describe particle dispersion. The so-called puff-particle model (PPM) retains the advantages of traditional puff models and at the same time is able to take into account the correct probability density function of the stochastic velocity components, with a computing time considerably less than that of particle models. The PPM is three-dimensional and it includes a Lagrangian approach for puff rise. The parametrisations cover stable, neutral and convective conditions. The model is shown to reproduce realistically the concentration patterns for a simple flow of homogeneous Gaussian turbulence. It is furthermore used to investigate the effect of an inhomogenity in surface roughness on dispersion characteristics.

Keywords: dispersion model, particle model, plume rise, puff model, atmospheric dispersion models, environmental impact assessment, plume dispersion, environmental pollution, modelling, inhomogenity, surface roughness, air pollution