Helicity sources in a rotating convection

Abstract

Convective flows from localized heater in a rotating layer were studied numerically in a three-dimensional non-stationary formulation. Distribution of helicity, its mean and fluctuating contributions were simulated for two specific regimes. In the first one the stable cyclonic vortex and intensive convective jet produce substantial amount of helicity near the axis of rotation. In the second one convective flow is more chaotic, cyclonic vortex appears at some distance from the center and as a result helicity is more dispersed in the lower layer of the fluid. Helicity in a described system is characterized by high level of pulsations. Spatial and temporal variations of helicity sources were analysed using equation for helicity balance. Time variations of viscous term and buoyancy term in helicity equation strongly exceed variations of other terms and the helicity time derivative. In a described system the buoyancy term is a source of helicity and viscous term is a sink. It was found that they are in antiphase and compensate each other.