Sreenivasan, B. and Davidson, P.A. (2008) On the formation of cyclones and anticyclones in a rotating fluid. Physics of Fluids, 20 (8). 085104. ISSN 1070-6631
Available under licence : See the attached licence file.
It is commonly observed that the columnar vortices that dominate the large scales in homogeneous, rapidly rotating turbulence are predominantly cyclonic. This has prompted us to ask how this asymmetry arises. To provide a partial answer to this we look at the process of columnar vortex formation in a rotating fluid and, in particular, we examine how a localized region of swirl (an eddy) can convert itself into a columnar structure by inertial wave propagation. We show that, when the Rossby number (Ro) is small, the vortices evolve into columnar eddies through the radiation of linear inertial waves. When the Rossby number is large, on the other hand, no such column is formed. Rather, the eddy bursts radially outward under the action of the centrifugal force. There is no asymmetry between cyclonic and anticyclonic eddies for these two regimes. However, cyclones and anticyclones behave differently in the intermediate regime of Ro~1. Here we find that the transition from columnar vortex formation to radial bursting occurs at lower values of Ro for anticyclones, with the transition for anticyclones occurring at Ro~0.5, and that for cyclones at Ro~2. Thus, in a homogeneous turbulence experiment conducted at, say, Ro=1, we would expect to see more cyclones than anticyclones. The reason for this asymmetry at Ro~1 is explained.
|Copyright, Publisher and Additional Information:||© 2008 American Institute of Physics. This is an author produced version of a paper published in Physics of Fluids. Uploaded in accordance with the publisher's self archiving policy.|
|Institution:||The University of Leeds|
|Academic Units:||The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds)|
|Depositing User:||Sherpa Assistant|
|Date Deposited:||06 Nov 2008 12:08|
|Last Modified:||08 Feb 2013 17:05|
|Publisher:||American Institute of Physics|