Author(s)

S. Heinz

Abstract

Lagrangian modelling of turbulent diffusion, buoyancy and chemical processes S. Heinz Fraunhofer Insitutfur Atmosphdriche Umweltforschung (IFU), Kreuzeckbahnstrafie 19, D-82467 Garmisch-Partenkirchen, Germany ABSTRACT Linear Lagrangian equations for turbulent motion and buoyancy are shown to be consistent with the Eulerian budget equations for the mean wind and potential temperature fields and their coupled variances. These equations take reference to a locally isotropic dissipation according to Kolmogorov theory and a return-to isotropy pressure redistribution according to Rotta. They permit a selfconsistent calculation of the flow in dependence on three dimensionless flow numbers. These flow numbers are the Prandtl number under neutral stratification Pr, the critical gradient Richardson number Ri^ and a new introduced number Ri^ The timescale of turbulent motion normalized to the vertical sheared horizontal mean wind is calculated within this approach in dependen

Keywords