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Vorticity production

Vorticity production. Axel Brandenburg, Fabio Del Sordo, Oliver Gressel, Chi-kwan Chan. Vorticity production. Forcing purely potential, where does w rms come from? Sort of small-scale vortex-dynamo problem One source is always viscosity

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Vorticity production

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  1. Vorticity production Axel Brandenburg, Fabio Del Sordo, Oliver Gressel, Chi-kwan Chan

  2. Vorticity production • Forcing purely potential, where does wrms come from? • Sort of small-scale vortex-dynamo problem • One source is always viscosity • Other sources: rotation, shear, baroclinicity, B-field

  3. Gaussian expansion waves Motivated by SN explosions Mee & Brandenburg (2006)

  4. No dynamo from potential flows No dynamo action in nearly potential flows (at least not fo far)

  5. No vorticity either (small Ma)

  6. Linear increase with rotation

  7. Clearly a large-scale effect Small-scale effect independent of W, but perhaps spurious?

  8. Similar growth with shear rate Spurious because of shearing sheet boundary conditions?

  9. Baroclinic effect

  10. …after first baroclinic encounter

  11. wrms even in isothermal case Federrath et al (1011)

  12. Spectra with NIRVANA well behaved at small scale Calculation by Oliver Gressel

  13. Calculations by Chi-kwan Chan

  14. The viscoclinic term Federrath+11 Gressel

  15. First viscoclinic encounter

  16. Same for m or n=const

  17. B field ignores irrotational partbut it also drives vorticity

  18. Conclusions • Vorticity unavoidable when compressible • Numerical effects surprisingly weak! • With baroclinicity: relative importance unclear • Magnetic field only due to vortical part

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