The oscillation modes of large-scale circulation in turbulent Rayleigh-B\'enard convection

We present measurement of the large-scale circulation (LSC) of turbulent Rayleigh-B\'enard convection of cubic cell. We found the reorientation events by rotation through the LSC orientation $\theta_0$ with a multi-peaked probability distribution $p(\theta_0)$, as predicted by the model presented by Brown and Ahlers (Phys. Fluids, 2008). In contrast to the results of oscillation modes in cylindrical cell, when the LSC was confined into one corner, the flow didn't exhibit the twisting and sloshing oscillation with a well-defined periodicity. The phase relation of $\theta_0$ at different heights in the cell was not fixed, so LSC was not in a plane. The sloshing displacement of the LSC from a center plane exhibited random switching between two states.