Eye Formation in Rotating Convection

• Main Authors: Oruba, L, Davidson, P. A, Dormy, E
• Format: Journal Article
• Language: English
• Published: 15-08-2016
• Subjects: Physics - Fluid Dynamics; Physics - Geophysics
• DOI: 10.48550/arxiv.1608.04234

We consider rotating convection in a shallow, cylindrical domain. We examine
the conditions under which the resulting vortex develops an eye at its core;
that is, a region where the poloidal flow reverses and the angular momentum is
low. For simplicity, we restrict ourselves to steady, axisymmetric flows in a
Boussinesq fluid. Our numerical experiments show that, in such systems, an eye
forms as a passive response to the development of a so-called eyewall, a
conical annulus of intense, negative azimuthal vorticity that can form near the
axis and separates the eye from the primary vortex. We also observe that the
vorticity in the eyewall comes from the lower boundary layer, and relies on the
fact the poloidal flow strips negative vorticity out of the boundary layer and
carries it up into the fluid above as it turns upward near the axis. This
process is effective only if the Reynolds number is sufficiently high for the
advection of vorticity to dominate over diffusion. Finally we observe that, in
the vicinity of the eye and the eyewall, the buoyancy and Coriolis forces are
negligible, and so although these forces are crucial to driving and shaping the
primary vortex, they play no direct role in eye formation in a Boussinesq
fluid.