A Lagrangian approach for modelling turbulent transport and chemistry

A Lagrangian two-particle model for the relative diffusion and mixing of two reactive species is proposed. The model has been tested for consistency in simple geometrical configurations and has been compared to experimental data, Eulerian first- and second-order closure models as well as to other Lagrangian models. The model includes the covariance between the two species and therefore gives better predictions of both diffusion and chemistry than first-order closure models or the one-particle model proposed by Chock and Winkler (1994a,b, Journal of Geophysical Research, 99 D1, 1019–1031, 99 D1, 1033–1041). The model is a generalisation of the model presented by Komori et al. (1991, Journal of Fluid Mechanics 228, 629–659). The results of the calculations, although preliminary in character, indicate that the proposed algorithm is robust and efficient, and yields satisfactory results in turbulence with slow to moderate chemistry.