A second-order Lagrangian stochastic model for particle trajectories in inhomogeneous turbulence

The second-order Lagrangian stochastic model of Du et al. for particle traj ectories in homogeneous turbulence is extended to inhomogeneous turbulence. The model is shown to be in good agreement with experimental dispersion da ta for laboratory-scale convective boundary layers and for a neutrally stab le wind-tunnel boundary layer. The results of numerical simulations suggest that finite Reynolds number effects are not important in determining the m ean concentrations of tracer particles dispersing in these flows. Estimates for the value of the Lagrangian velocity structure function constant, obta ined by optimizing model agreement with experimental dispersion data, are f ound to be flow-dependent.