Author(s)

E. Mastorakos

Abstract

The conditional moment closure approach for atmospheric pollution problems E. Mastorakos Engineering Depariment, Cambridge University, UK Abstract In this paper, the Conditional Moment Closure is applied to simple problems of reacting flows in the atmosphere with the CBM-IV chemical mechanism in order to evaluate the effect of small-scale segregation on the evolution of the mean pollutant concentrations. The CMC method uses modelled transport equations for conditional averages of the reactive scalars, with the conditioning done on a conserved scalar. Macro-mixing is taken into account by solving the transport equation of the time-averaged conserved scalar, while micro-mixing is included in CMC theory in models for the scalar dissipation rate. The results show that the usual assumption of well-mixed reactants is valid for the species that react over long timescales, but for species aftected by fast chemistry (e.g. radicals such as HOJ, the differences between the CMC predictions and the well-mix

Keywords