Study of the PDFs of a Stably Stratified Large-Eddy Simulation

The turbulence of the first GABLS LES case is studied through Probability Density Functions (PDF) and compared to the ones corresponding to the Convective regime (with and without mean wind).

The pdf's are computed for 1 hour within the steady-state regime for each simulation. Three levels are considered: the surface layer, the middle and the top of the boundary layer.

The statistics computed from the pdf's are compared to those obtained by the classical averaging method used in the LES outputs. These statistics are also used to identify the gaussianity of the pdf's. The analysis show that the studied cases have approximately gaussian pdf's except for the no-wind convective case. The characteristic functions, the correlation functions (from which the integral scale is found) and spectra are also computed to describe the turbulence. Some tests have been done such as the effect on the pdf's when the resolution is increased. The Ergodic theorem and the statistical dependence of some of the variables is checked. The differences between the regimes will be shown.