Dependence of the large-scale vortex instability on latitude, stratification and domain size

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http://hdl.handle.net/10138/29166

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J. Mantere , M , J. Käpylä , P & Hackman , T 2011 , ' Dependence of the large-scale vortex instability on latitude, stratification and domain size ' Astronomische Nachrichten , vol. 332 , no. 9/10 , pp. 876 – 882 . DOI: 10.1002/asna.201111620

Julkaisun nimi: Dependence of the large-scale vortex instability on latitude, stratification and domain size
Tekijä: J. Mantere, Maarit; J. Käpylä, Petri; Hackman, Thomas
Muu tekijä: University of Helsinki, Department of Astronomy (-2009)
University of Helsinki, Department of Astronomy (-2009)
University of Helsinki, Department of Physics
Päiväys: 2011
Kieli: eng
Sivumäärä: 7
Kuuluu julkaisusarjaan: Astronomische Nachrichten
ISSN: 0004-6337
URI: http://hdl.handle.net/10138/29166
Tiivistelmä: In an earlier study, we reported on the excitation of large-scale vortices in Cartesian hydrodynamical convection models subject to rapid enough rotation. In that study, the conditions for the onset of the instability were investigated in terms of the Reynolds (Re) and Coriolis (Co) numbers in models located at the stellar North pole. In this study, we extend our investigation to varying domain sizes, increasing stratification, and place the box at different latitudes. The effect of the increasing box size is to increase the sizes of the generated structures, so that the principal vortex always fills roughly half of the computational domain. The instability becomes stronger in the sense that the temperature anomaly and change in the radial velocity are observed to be enhanced. The model with the smallest box size is found to be stable against the instability, suggesting that a sufficient scale separation between the convective eddies and the scale of the domain is required for the instability to work. The instability can be seen upto the colatitude of 30 degrees, above which value the flow becomes dominated by other types of mean flows. The instability can also be seen in a model with larger stratification. Unlike the weakly stratified cases, the temperature anomaly caused by the vortex structures is seen to depend on depth.
Avainsanat: astro-ph.SR
115 Astronomy, Space science
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