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SUMMARY:Contributed talk: Thermo-compositional convection and dynamos in r
 otating spherical shells - Radostin Simitev (University of Glasgow)
DTSTART:20221201T114500Z
DTEND:20221201T121500Z
UID:TALK192134@talks.cam.ac.uk
DESCRIPTION:Convection and magnetic field generation in the Earth and plan
 etary interiors are driven by both thermal and compositional gradients. In
  this work numerical simulations of finite-amplitude double-diffusive conv
 ection and dynamo action in rapidly rotating spherical shells full of inco
 mpressible two-component electrically-conducting fluid are reported. Four 
 distinct regimes of rotating double-diffusive convection can be identified
  in linear analysis and these are found to persist significantly beyond th
 e onset of instability while their regime transitions remain abrupt. In th
 e semi-convecting and the fingering regimes characteristic flow velocities
  are small compared to those in the thermally- and compositionally-dominat
 ed overturning regimes\, while zonal flows remain weak in all regimes apar
 t from the thermally-dominated one. Compositionally-dominated overturning 
 convection exhibits significantly narrower azimuthal structures compared t
 o all other regimes while differential rotation becomes the dominant flow 
 component in the thermally-dominated case as driving is increased. Dynamo 
 action occurs in all regimes apart from the regime of fingering convection
 . While dynamos persist in the semi-convective regime they are very much i
 mpaired by small flow intensities and very weak differential rotation in t
 his regime which makes poloidal to toroidal field conversion problematic. 
 The dynamos in the thermally-dominated regime include oscillating dipolar\
 , quadrupolar and multipolar cases similar to the ones known from earlier 
 parameter studies. Dynamos in the compositionally-dominated regime exhibit
  subdued temporal variation and remain predominantly dipolar due to weak z
 onal flow in this regime.\n&nbsp\;\nRadostin D. Simitev\, James Mather & L
 uis Silva\nSchool of Mathematics and Statistics\, University of Glasgow\, 
 Glasgow\, UK\n&nbsp\;
LOCATION:Seminar Room 1\, Newton Institute
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