Flux-gradient relationship for turbulent dispersion over complex terrain
- 1Istituto FISBAT/CNR, Via Gobetti 101, 40129 Bologna, Italy
- 2Istituto ISIATA/CNR, Strada per Arnesano, 73100 Lecce, Italy
- 3Istituto ICG/CNR, corso Fiume 4, 10133 Torino, Italy
- 4Dip. Scienze e tec. Avanz., Universitá di Alessandria, Corso Borsalino 54, 15100 Alessandria, Italy
- 5ENEL/CRAM, Servizio Ambiente, Via Rubattino 54, 20134 Milano, Italy
Abstract. The transfer of a passive tracer in inhomogeneous turbulent flow is investigated. Starting from Lumley's constitutive equation, we derived an expression for the ratio between the effective eddy diffusivity K and eddy diffusivity K as a function of three length scales characterizing the local turbulence structure, flux variations and turbulence inhomogeneities. The theoretical predictions for the one-dimensional case of inhomogeneous symmetric turbulence were validated through a comparison with the numerical results of a Lagrangian particle model simulating a wind tunnel experiment of dispersion in the lee of an idealized two-dimensional hill. A qualitative agreement is reached between the theoretical evaluation of K and the value obtained from the numerical simulation.