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Model z by computation and taylor's condition

 

作者: D. Jault,  

 

期刊: Geophysical & Astrophysical Fluid Dynamics  (Taylor Available online 1995)
卷期: Volume 79, issue 1-4  

页码: 99-124

 

ISSN:0309-1929

 

年代: 1995

 

DOI:10.1080/03091929508228993

 

出版商: Taylor & Francis Group

 

关键词: αω dynamos;Taylor's condition, model Z;earth's core

 

数据来源: Taylor

 

摘要:

The spherical geodynamo model of Braginsky (1978) is re-integrated. The original model of Braginsky modified the Taylor's condition to include the influence of viscous core-mantle coupling. Reinstating also the Ø-component of momentum ∂ωG(s)/∂t [where ωG(s) is the geostrophic shear] in the expression for the modified Taylor condition makes possible the investigation of solutions for small viscosities. Above a critical dynamo numberDc, the solution enters a viscously-limited branch (“Ekman” or “coupling” branch) and, eventually, asDis further increased, jumps to a strong-field branch. The original numerical solution of Braginsky belongs to the latter branch and is duplicated. But, with weak viscosities, the solution on that branch is proved inviscid. In that inviscid limit, Braginsky's model meets the Taylor's condition. The same code is used to re-investigate another αω dynamo model defined by a simpler choice of α and ω effects [α =Rα cos , ω =Rω(r– 1)]

 

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