Large-eddy simulations of turbulent Rayleigh-Benard convection were conducted for a fluid of Prandtl number ́
Pr = 0.7 confined in a cube, for Rayleigh numbers of 106 and 108. The model solves the unsteady Navier-Stokes
equations under the Boussinesq approximation, using a dynamic Smagorinsky model with a Lagrangian averaging
technique for the subgrid terms. Under fully developed conditions the flow topology is characterized by a
large-scale circulation (LSC) developing in a plane containing one of the diagonals of the cell, while two
counter-rotating vortices consequently develop in the other diagonal plane, resulting in a strong inflow at the
horizontal midplane. This flow structure is not static, with the LSC undergoing nonperiodic reorientations, or
switching, between the two diagonal planes; hence, we supplement the observations of the three-dimensional
time-averaged flow structures with single point measurements (time series) to shed light on the dynamics of
the reorientations. For all observations, this switching results from a lateral rotation of the LSC in which
some finite time spent in a transient state where the large-scale circulation is parallel to one set of side walls;
there are, importantly, no observations consistent with so-called cessations of the LSC, in which it decays
and then reforms in another plane without such a rotation. The average switching rate for the LSC is in
excellent agreement with the results of Bai et al. [K. Bai, D. Ji, and E. Brown, Phys. Rev. E 93, 023117
(2016)]
