Skip to main content
Article thumbnail
Location of Repository

Prandtl-number dependence of convection-driven dynamos in rotating spherical fluid shells

By R. Simitev and F.H. Busse

Abstract

The value of the Prandtl number P exerts a strong influence on convection-driven dynamos in rotating spherical shells filled with electrically conducting fluids. Low Prandtl numbers promote dynamo action through the shear provided by differential rotation, while the generation of magnetic fields is more difficult to sustain in high-Prandtl-number fluids where higher values of the magnetic Prandtl number P<sub>m</sub> are required. The magnetostrophic approximation often used in dynamo theory appears to be valid only for relatively high values of P and P<sub>m</sub>. Dynamos with a minimum value of P<sub>m</sub> seem to be most readily realizable in the presence of convection columns at moderately low values of P. The structure of the magnetic field varies strongly with P in that dynamos with a strong axial dipole field are found for high values of P while the energy of this component is exceeded by that of the axisymmetric toroidal field and by that of the non-axisymmetric components at low values of P. Some conclusions are discussed in relation to the problem of the generation of planetary magnetic fields by motions in their electrically conducting liquid cores

Topics: QC
Publisher: Cambridge University Press
Year: 2005
OAI identifier: oai:eprints.gla.ac.uk:13305
Provided by: Enlighten

Suggested articles

Citations

  1. 2002b Is low Rayleigh number convection possible in the Earth’s core? doi
  2. (2001). A h l e r s ,G .&X u ,X doi
  3. (1997). A r d e s ,M . ,B u s s e ,F .H .&W i c h t ,J doi
  4. (1983). A second-order correlation approximation for thermal conductivity and Prandtl number of free turbulence. doi
  5. (1997). An Earth-like numerical dynamo model.
  6. B u s s e ,F .H .&C u o n g ,P .G .1977 Convection in rapidly rotating spherical fluid shells. doi
  7. (2004). B u s s e ,F .H .&S i m i t e v ,R doi
  8. (2001). Buoyancy driven convection in rotating spherical shells and its dynamo action. doi
  9. (1989). Convection driven magnetohydrodynamic dynamos in rotating spherical shells. doi
  10. (2002). Convection flows in rapidly rotating spheres and their dynamo action. doi
  11. (2003). Convection in rotating spherical shells and its dynamo action. doi
  12. (1999). Convection-driven quadrupolar dynamos in rotating spherical shells, doi
  13. (2001). Dynamics of convection and dynamos in rotating spherical fluid shells. Fluid Dyn. doi
  14. (2003). Dynamo action and its temporal variation inside the tangent cylinder in MHD dynamo simulations. doi
  15. (2000). Effects of driving mechanisms in geodynamo models. doi
  16. (1995). Equations governing convection in Earth’s core and the geodynamo. doi
  17. (1997). Finite amplitude convection in rotating spherical fluid shells. doi
  18. (2002). From stable dipolar towards reversing numerical dynamos. doi
  19. (1997). Generation mechanism of a dipole field by a magnetohydrodynamic dynamo. doi
  20. (1990). Generation of magnetic field by convection in a rotating spherical fluid shell of infinite Prandtl number. doi
  21. (2000). Hemispherical dynamos generated by convection in rotating spherical shells. doi
  22. (1961). Hydrodynamic and Hydromagnetic Stability. doi
  23. I s h i h a r a ,N .&K i d a ,S .2002 Dynamo mechanism in a rotating spherical shell: competition between magnetic field and convection vortices. doi
  24. (2002). Inner-core conductivity in numerical dynamo simulations. doi
  25. K a t a y a m a ,J .S . ,M a t s u s h i m a ,M .&H o n k u r a ,Y .1999 Some characteristics of magnetic field behavior in a model of MHD dynamo thermally driven in a rotating spherical shell. doi
  26. (1999). Numerical modeling of the geodynamo: a systematic parameter study. doi
  27. (1999). Numerical modeling of the geodynamo: mechanism of field generation and equilibration. doi
  28. (1998). On convection driven dynamos in rotating spherical shells. doi
  29. (1995). On coupling between the Poincar´ e equation and the heat equation: no-slip boundary condition. doi
  30. (1994). On coupling between the Poincar´ e equation and the heat equation. doi
  31. (1987). On the onset of convection in rotating spherical shells. doi
  32. (2003). Patterns of convection in rotating spherical shells. doi
  33. (2000). Regular and chaotic spherical dynamos. doi
  34. s s e ,F .H .&S i m i t e v ,R .2005 Convection in rotating spherical fluid shells and its dynamo states. doi
  35. (2002). The origin of geomagnetic jerks. doi
  36. (1998). Thermally driven MHD dynamo in a rotating spherical shell. doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.