Diffusion‐Free Scaling in Rotating Spherical Rayleigh‐Bénard Convection

What is it about?

Direct numerical simulations are employed to reveal three distinctly different flow regions in rotating spherical Rayleigh-B\'enard convection. In the low-latitude region I vertical (parallel to the axis of rotation) convective columns are generated between the hot inner and the cold outer sphere. The mid-latitude region II is dominated by vertically aligned convective columns formed between the Northern and Southern hemispheres of the outer sphere. The diffusion-free scaling, which indicates bulk-dominated convection, originates from this mid-latitude region. In the equator region III the vortices are affected by the outer spherical boundary and are much shorter than in region II.

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Why is it important?

We identify 3 flow regions in spherical RB convection: High-latitudes (vertical columns), Mid-latitudes (aligned columns), and Equator (shorter vortices). We demonstrate diffusion-free scaling originates from mid-latitude region, with aligned vortices between Northern and Southern hemispheres.