Development of a new numerical simulation model of an integrated system for the convecting mantle and outer-core

2015 Fiscal Year Final Research Report

• Project/Area Number: 26610144
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Yoshida Masaki 国立研究開発法人海洋研究開発機構, 地球深部ダイナミクス研究分野, 主任研究員 (00371716)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: マントル / コア / 外核 / 熱対流 / 二層対流 / 数値シミュレーション / 粘性率 / 熱膨張係数

Outline of Final Research Achievements

A series of high-resolution numerical simulations of Rayleigh-Bénard convection with a highly viscous outer layer (HVL) and a low-viscosity inner layer (LVL) in 2-D spherical-shell geometry were performed to investigate the dynamics of convection between two layers with large viscosity contrasts up to 10**3. Results show that the mechanical coupling (MC) mode is dominant in two-layer convection when the viscosity contrast between the two layers is sufficiently small, and it weakens, becoming closer to the thermal coupling (TC) mode, as the LVL viscosity decreases. This transition from MC to TC modes results in a stabilizing of the convection speed and the heat transport efficiency of the HVL. Our numerical results imply that thermal convection in the mantle controls the heat transport efficiency of the two-layer solid-earth system and controls the convective style in the outer core.

Free Research Field

地球惑星内部物理学, 地球進化史, 地震テクトニクス, 数値流体力学