Küppers-Lortz transition at high dimensionless rotation rates in rotating Rayleigh-Bénard convection

We show that for rotating Rayleigh-B\'enard convection over a range of dimensionless rotation rates 2702500, bulk convection structures are K\"uppers-Lortz unstable near onset. We used optical shadowgraph imaging to visualize the pattern dynamics, found switching angles of approximately 60^∘{}, and observed separate spatial domains where switchings took place at different times. The characteristic switching frequencies were found to depend weakly on the rotation rate. Finite-size and boundary effects were observed to complicate the switching dynamics close to onset.