Jack Atkinson

Scientist, Archer

Eye dynamics in rotating convection

2019
Eye dynamics in rotating convection


The subject of eye formation - the development of a region of calm, reversed (or subsiding) flow, localised to the central axis of a vortex - is a particularly interesting problem. It has attracted the attention of geophysical fluid dynamicists for a long time. The phenomenon is perhaps most widely recognised in tropical cyclones such as Hurricane Isabel shown above, photographed from the International Space Station (source). Similar structures have perhaps been observed in columnar atmospheric vortices as well, however, such as tornadoes, dust devils, and waterspouts.

Though much work has been done to understand these phenomena, there is still a lack of consensus about how eyes form at the centre. A recent paper suggests that eyes forms as a passive response to vorticity from the lower boundary layer being advected into the flow. This is illustrated below.

schematic

Building on these ideas we show that the eye that forms at the centre of a shallow vortex can support inertial waves leading to oscillatory behaviour of the eye at the centre. Such oscillations may have been observed in real cyclones, though further work will be required to confirm this. It is also interesting to ask if these oscillations might also occur in columnar vortices, perhaps leading to vortex breakdown.

The results of this work are presented in the following publication:

2019 - APS Physical Review Fluids
Atkinson JW, Perry, JEG, and Davidson PA
The Dynamics of a Trapped Vortex in Rotating Convection
DOI: 10.1103/PhysRevFluids.4.074701    –    PDF