Some characteristics of magnetic field behavior in a model of MHD dynamo thermally driven in a rotating spherical shell

Katayama, Joichi; Matsushima, Masaki; Honkura, Yoshimori

doi:10.1016/s0031-9201(98)00152-6

Cited by 30 publications

(15 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…(1998), Sakuraba & Kono (1999), Katayama et al . (1999), Kageyama & Sato (1997a{c), Kitauchi & Kida (1998), Kida & Kitauchi (1998a;b) and Olson et al .…”

Section: Numerical Results In the Busse{zhang Regimementioning

confidence: 99%

Convection–driven geodynamo models

Jones

2000

Philosophical Transactions of the Royal Society of London. Seri

125

View full text Add to dashboard Cite

There has been signi cant progress in the development of numerical geodynamo models over the last ve years. Advances in computer technology have made it possible to perform three-dimensional simulations, with thermal or compositional convection as the driving mechanism. These numerical simulations give reasonable results for the morphology and strength of the eld at the core{mantle boundary, and the models are also capable of giving reversals and excursions which can be compared with palaeomagnetic observations; they also predict di¬erential rotation between the inner core and the mantle.However, there are still a number of fundamental problems associated with the simulations, which are proving hard to overcome. Despite the advances in computing power, the models are still expensive and take a long time to run. This problem may diminish as faster machines become available, and new numerical methods exploit parallelization e¬ectively, but currently there are no practical schemes available which work at low Ekman number.Even with turbulent values of the di¬usivities (and the question of whether isotropic di¬usivities are appropriate is still unresolved), the appropriate dynamical regime has not yet been reached. In consequence, modelling assumptions about the nature of the ®ow near the boundaries have to be made, and di¬erent choices can have profound e¬ects on the dynamics. The nature of large-scale magnetoconvection at small E is still not well understood, and until we have more understanding of this issue, it will be di¯cult to have a great deal of con dence in the predictions of the numerical models.

show abstract

“…(1998), Sakuraba & Kono (1999), Katayama et al . (1999), Kageyama & Sato (1997a{c), Kitauchi & Kida (1998), Kida & Kitauchi (1998a;b) and Olson et al .…”

Section: Numerical Results In the Busse{zhang Regimementioning

confidence: 99%

Convection–driven geodynamo models

Jones

2000

Philosophical Transactions of the Royal Society of London. Seri

125

View full text Add to dashboard Cite

show abstract

“…The onset of convection driven dynamos in the case P = 1 has been explored in numerous papers in the past. We refer to the work of Kageyama and Sato (1997), Kida and Kitauchi (1998), Ishihara and Kida (2002), Busse et al (1998), Christensen et al (1999), Olson et al (1999), Katayama et al (1999), Takahashi et al (2003), , . In particular the results of the latter two papers can be compared well with the results presented in the following since only the Prandtl number differs among the parameters of the computations.…”

Section: The Onset Of Dynamo Action For Different Prandtl Numbersmentioning

confidence: 99%

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

Simitev¹,

Busse²

2005

J. Fluid Mech.

View full text Add to dashboard Cite

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 m are required. The magnetostrophic approximation often used in dynamo theory appears to be valid only for relatively high values of P and P m . Dynamos with a minimum value of P m 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.

show abstract

“…Global 3D dynamo models designed to study the Earth's core were developed a decade later (Glatzmaier & Roberts 1995a, Kageyama & Sato 1997, Kuang & Bloxham 1997, Kida et al 1997, Busse et al 1998, Christensen et al 1998, Sakuraba & Kono 1999, Katayama et al 1999, Hollerbach 2000, Christensen et al 2001. Simpler and more affordable models that are not globally 3D or not fully time dependent have also provided valuable insights (Cuong & Busse 1981, Zhang & Busse 1988, Jones et al 1995, Kageyama et al 1995, Sarson et al 1997; however, they are accurate only for weakly driven convection.…”

Section: Brief Historymentioning

confidence: 99%

Geodynamo Simulations—How Realistic Are They?

Glatzmaier

2002

Annu. Rev. Earth Planet. Sci.

134

104

View full text Add to dashboard Cite

The past seven years have seen significant advances in computational simulations of convection and magnetic field generation in the Earth's core. Although dynamically self-consistent models of the geodynamo have simulated magnetic fields that appear in some ways quite similar to the geomagnetic field, none are able to run in an Earth-like parameter regime because of the considerable spatial resolution that is required. Here we discuss some of the subtle compromises that have been made in current models and propose a grand challenge for the future, requiring significant improvements in numerical methods and spatial resolution.

show abstract

Some characteristics of magnetic field behavior in a model of MHD dynamo thermally driven in a rotating spherical shell

Cited by 30 publications

References 20 publications

Convection–driven geodynamo models

Convection–driven geodynamo models

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

Geodynamo Simulations—How Realistic Are They?

Contact Info

Product

Resources

About