2D and quasi-2D DNS of turbulent convection in vertical layers

Turbulent Rayleigh-Benard convection in a bounded vertical layer of size 1×Г×1 (Г is the aspect ratio that characterizes the layer thickness) is studied by two-dimensional (2D) and quasi-two-dimensional (Q2D) direct numerical simulations (DNS) mainly performed for Rayleigh number Ra=2.2·10 9 and Prandtl number Pr=7. The simulation results are verified by comparison with the results of an experimental investigation into the convective flow of water in a rectangular box heated from below with dimensions 250× d ×250 mm 3 ( d varied from 15 to 50 mm). It is shown that, even in the framework of a crude model of linear friction used in the Q2D model, consideration of friction on lateral boundaries allows us to get a realistic structure of the turbulent flow with the aspect ratio . In addition, the Q2D model correctly describes the dynamics of the large-scale flow and reproduces the experimental power spectral density of velocity fluctuations.