The Simulation of Dispersion by Convective Turbulence in the Atmosphere

Abstract

A large eddy model gives a numerical simulaton of the large scale motions in a turbulent flow by solving the set of Navier-Stokes equations from which small scale motions are removed by filtering [1]. Here we apply this approach to calculate turbulence in the convective atmospheric boundary layer. This type of turbulence, which generally occurs when the boundary layer is heated from below, is dominated by large scale structures and therefore well suited to simulation by large eddy modeling. These large scale structures are called thermals and they consist of rising plumes of relatively warm air. They start at the surface and they travel towards the top of the boundary layer. The thermals are embedded in regions of relatively cold and slowly subsiding air. These characteristics are well reproduced by a large eddy model as shown in [2].