Author(s)

S. Heinz & E. Schaller

Abstract

Modeling of buoyancy and chemical reactions in a Lagrangian framework S. Heinz, E. Schaller Fraunhofer Institut fur Atmosphdrische Umweltforschung, Kreuzeckbahnstr. 19, D-82467 Garmisch-Partenkirchen, Germany ABSTRACT A conceptional approach was developed to describe turbulent diffusion in a high-Reynolds number flow in the Lagrangian framework by stochastic differential equations for particle motion. With respect to practical applications buoyancy effects and chemical reactions have to be considered additionally. It is described here, how this can be handled in the Lagrangian concept, where consistency between the Lagrangian and the Eulerian view is guaranteed for the means and variances of the quantities considered. This is achieved by calculating the coefficients appearing in the Lagrangian equations based on a turbulent timescale, which can be related to gradients of mean wind and temperature. INTRODUCTION It has been demonstrated e. g. by van Dop

Keywords