Core precession: flow structures and energy
Core precession: flow structures and energy
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核心进动：流动结构和能量
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
J. R. Dunn
中科院分区：
文献类型：
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作者：
J. Vanyo;J. R. Dunn
摘要
使用扁率（\(b/a\)）为\(1/400\)的进动充液扁球体进行的实验拓展并阐明了早期研究。这些实验得出了有助于估算地球液核内流动的流动数据。观测到的流动情况展示并证实了一个在进动时具有逆行漂移且滞后于腔体（地幔）轴的近似刚性液球。观测到的滞后角与为刚性球体计算出的滞后角的相似性，以及早期的能量耗散研究，都支持使用刚性球体分析模型来预测地核 - 地幔边界（CMB）内的能量耗散和一级流动。二阶边界层和内部圆柱状流动结构也被拍摄和测量。在近地参数下，内部流动从不紊乱或不稳定，尽管在边界层内观测到了复杂且瞬态的流动模式。为解释地球净热损失和地球发电机的维持而提出的其他机制通常需要接受一些关键但未经证实的前提。进动和地核 - 地幔边界的构造是确定且精确已知的。分析上的困难一直是障碍。实验展示了进动和扁率的结果，为验证分析和数值模型提供了标准，并且通过仔细的比例换算可能会产生对地球深部内部的直接认识。
SUMMARY Experiments using a precessing liquid-filled oblate spheroid with ellipticity (ab)/a= 1/400 extend and clarify earlier research. They yield flow data useful for estimating flows in the Earth’s liquid core. Observed flows illustrate and confirm a nearly rigid liquid sphere with retrograde drift and lagging a cavity (mantle) axis in precession. The similarities of the observed lag angle with that computed for a rigid sphere, and earlier energy dissipation research both support the use of a rigid sphere analytical model to predict energy dissipation and first-order flow within the core‐mantle boundary (CMB). Second-order boundary layer and interior cylindrical flow structures also are photographed and measured. Interior flows are never turbulent or unstable at near-Earth parameters, although complex and transient flow patterns are observed within the boundary layer. Other mechanisms proposed to explain net heat loss from the Earth and maintenance of the geodynamo typically require acceptance of some critical but unproven premise. Precession and CMB configuration are known with certainty and precision. Analytical diculties have been the obstacle. Experiments illustrate the consequences of precession and ellipticity, provide criteria for validating analytical and numerical models, and may yield direct knowledge of the Earth’s deep interior with careful scaling.