Inverse centrifugal effect induced by collective motion of vortices in rotating thermal convection

Abstract When a fluid system is subject to strong rotation, centrifugal motion expected, i.e., denser (lighter) moves outward (inward) from (toward) the axis of rotation. Here we demonstrate, both experimentally and numerically, existence an unexpected warm lighter vortices in rotating thermal convection. This anomalous vortex occurs under rapid rotations when buoyancy sufficiently induce symmetry-breaking vorticity field, cold anticyclones overrides that cyclones. We show through hydrodynamic interactions densely distributed can self-aggregate into coherent clusters exhibit collective this flow regime. Interestingly, correlation velocity fluctuations within cluster scale-free, with length being proportional ( ≈ 30%) length. Such long-range leads counterintuitive vortices. Our study brings insights dynamics are widely present nature.