Rapidly rotating Rayleigh-Bénard convection with a tilted axis

Area of Science:

• Geophysics and Planetary Science
• Fluid Dynamics
• Atmospheric Science

Background:

• Understanding fluid dynamics in rotating systems is crucial for modeling planetary atmospheres.
• Convective processes in rotating fluids are influenced by the orientation of the rotation axis relative to gravity.

Purpose of the Study:

• To numerically explore the convective dynamics of a rapidly rotating, heated incompressible fluid.
• To investigate the influence of rotation axis tilt (ϕ) on fluid behavior and identify distinct convective regimes.

Main Methods:

• Numerical simulations of an incompressible fluid heated from below.
• Free-slip horizontal plates and periodic lateral boundary conditions were employed.
• The rotation axis was tilted with respect to the gravity vector, with the angle ϕ varying.

Main Results:

• Identified three convective regimes: sheared winds (ϕ=0°), a cyclonic vortex (45° ≤ ϕ ≤ 90°), and a new intermediate regime.
• The intermediate regime features vertically sheared winds organized in tilted bands, with weaker heat transport than vortex regimes.
• Coexistence of the banded and vortex solutions was observed for intermediate ϕ values (45°–60°), dependent on initial conditions.

Conclusions:

• The tilt angle of the rotation axis significantly dictates the convective dynamics in rotating fluids.
• A novel intermediate regime with banded, sheared winds was discovered.
• These findings have potential implications for understanding the dynamics of rapidly rotating planetary atmospheres.