论文标题

在存在垂直磁场的情况下,麦克斯韦 - 卡塔内诺流体的对流不稳定

The convective instability of a Maxwell-Cattaneo fluid in the presence of a vertical magnetic field

论文作者

Eltayeb, I. A., Hughes, D. W., Proctor, M. R. E.

论文摘要

我们研究了受垂直均匀磁场的贝纳德层的不稳定性,其中流体遵守麦克斯韦 - 卡塔内诺(MC)热通量温度关系。我们将Bissell(Proc。R.Soc。A,472:20160649,2016)的工作扩展到磁性prandtl Number $ p_m $的非零值。随着非零$ p_m $,分散关系的顺序增加,导致行为更加丰富。 Chandrasekhar Number $ Q $的大价值的渐近分析证实,当$ C Q Q^{1/2} $为$ O(1)$时,MC效应变得很重要,其中$ c $是Maxwell-Cattaneo编号。在此制度中,我们得出了一个独立于$ Q $的缩放系统。当$ cq^{1/2} $很大时,结果与prandtl Number $ p \ to \ infty $的限制中的管理方程衍生的结果一致,with $ p_m $ $ pinite;在这里,我们确定了一种新的不稳定性模式,这既不是由于惯性和诱导效应。在大型$ p_m $制度中,我们展示了如何在不同水平尺度的振荡模式之间发生过渡。对于$ q \ gg 1 $,小额值为$ p $,我们表明关键的瑞利号码在$ p $中是非单调的,前提是$ c> 1/6 $。尽管对无应力边界进行了对本文的分析,但可以证明其他类型的机械边界条件给出了相同的领先顺序结果。

We study the instability of a Bénard layer subject to a vertical uniform magnetic field, in which the fluid obeys the Maxwell-Cattaneo (MC) heat flux-temperature relation. We extend the work of Bissell (Proc. R. Soc. A, 472: 20160649, 2016) to non-zero values of the magnetic Prandtl number $p_m$. With non-zero $p_m$, the order of the dispersion relation is increased, leading to considerably richer behaviour. An asymptotic analysis at large values of the Chandrasekhar number $Q$ confirms that the MC effect becomes important when $C Q^{1/2}$ is $O(1)$, where $C$ is the Maxwell-Cattaneo number. In this regime, we derive a scaled system that is independent of $Q$. When $CQ^{1/2}$ is large, the results are consistent with those derived from the governing equations in the limit of Prandtl number $p\to \infty$ with $p_m$ finite; here we identify a new mode of instability, which is due neither to inertial nor induction effects. In the large $p_m$ regime, we show how a transition can occur between oscillatory modes of different horizontal scale. For $Q \gg 1$ and small values of $p$, we show that the critical Rayleigh number is non-monotonic in $p$ provided that $C>1/6$. While the analysis of this paper is performed for stress-free boundaries, it can be shown that other types of mechanical boundary conditions give the same leading order results.

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