Weakly non-Boussinesq convection in a gaseous spherical shell.
Weakly non-Boussinesq convection in a gaseous spherical shell.
复制标题
气态球壳中的弱非布辛涅斯克对流。
DOI：
10.1103/physreve.96.033104
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
P. Garaud
中科院分区：
文献类型：
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作者：
Lydia Korre;N. Brummell;P. Garaud
我们通过使用Boussinesq形式（Spiegel和Veronis， Astrophys）运行3D直接数值模拟，研究了与球壳中弱可压缩对流相关的动力学。[j].中国科学：地球科学，2016,(5):387 - 387 .]基于天体物理问题，我们假设存在一个有限绝热温度梯度∇T_{ad}，并对内边界固定通量和外边界固定温度的温度采用混合边界条件。这种设置本质上比具有固定温度边界条件的平行板之间的液体的瑞利-巴萨姆德对流更标准的情况更不对称。存在大量不对称的条件会导致对流性质的巨大变化，我们在这里证明了这一点。气流可以变成压力而不是浮力主导，导致异常热传输的上升流动。与直觉相反的是，背景温度梯度∇T[over¯]可以形成一个亚绝热层（其中g·∇T[over¯]<g·∇T_{ad}，其中g为重力），尽管在壳上的每个点对流仍然很强烈。这表明高度的非定域性。
We examine the dynamics associated with weakly compressible convection in a spherical shell by running 3D direct numerical simulations using the Boussinesq formalism [Spiegel and Veronis, Astrophys. J. 131, 442 (1960)AJLEEY0004-637X10.1086/146849]. Motivated by problems in astrophysics, we assume the existence of a finite adiabatic temperature gradient ∇T_{ad} and use mixed boundary conditions for the temperature with fixed flux at the inner boundary and fixed temperature at the outer boundary. This setup is intrinsically more asymmetric than the more standard case of Rayleigh-Bénard convection in liquids between parallel plates with fixed temperature boundary conditions. Conditions where there is substantial asymmetry can cause a dramatic change in the nature of convection and we demonstrate that this is the case here. The flows can become pressure- rather than buoyancy-dominated, leading to anomalous heat transport by upflows. Counterintuitively, the background temperature gradient ∇T[over ¯] can develop a subadiabatic layer (where g·∇T[over ¯]<g·∇T_{ad}, where g is gravity) although convection remains vigorous at every point across the shell. This indicates a high degree of nonlocality.