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Effect of Differential Rotation of Oscillating Inner Core on Steady Flow Instability in a Rotating Sphere
Microgravity Science and Technology ( IF 1.8 ) Pub Date : 2020-06-20 , DOI: 10.1007/s12217-020-09806-y
S.V. Subbotin , V.G. Kozlov

A comparative analysis of steady flow excited by an oscillating core in a rotating spherical cavity with a liquid is carried out in different cases: when the core is free and performs differential rotation, and when the core differential rotation is absent. In the cavity reference frame the core, whose density is less than the density of the liquid, oscillates near the cavity center under the action of transverse to the rotation axis external force field. In both cases, the oscillations lead to the appearance of almost two-dimensional axisymmetric azimuthal steady flow, with several inflection points in the velocity profile. An increase in the amplitude of core oscillations leads to a loss of stability of the axisymmetric flow. In the supercritical region, there is a series of threshold transitions associated with various instability modes. The instability manifests itself in the development of an azimuthal periodic system of vortices elongated parallel to the rotation axis. The modes differ in an azimuthal wavenumber, the location of the vortices (distance from the axis of rotation), and the azimuthal drift rate of the vortex system relative to the cavity. It is shown that the core differential rotation modifies the azimuthal velocity profile, resulting in a change in the instability thresholds. Due to an additional azimuthal flow, the drift velocity of the same type vortices in the two cases is different. The effect of the core differential rotation on the dispersion relations for various instability modes has been investigated.



中文翻译:

摆动内芯的微分旋转对旋转球体内稳态流动不稳定性的影响

在不同情况下,当芯子处于自由状态并执行差速旋转时,以及当芯子不存在差速旋转时,由摆动的芯子在带有液体的旋转球形腔中激发的稳态流进行比较分析。在腔参考系中,密度小于液体密度的芯在横向于旋转轴外力场的作用下在腔中心附近振荡。在这两种情况下,振荡都会导致出现几乎二维的轴对称方位稳定流,并在速度曲线中出现多个拐点。岩心振荡幅度的增加导致轴对称流稳定性的损失。在超临界区,存在一系列与各种不稳定性模式相关的阈值转变。这种不稳定性表现在平行于旋转轴延伸的涡旋的方位角周期性系统的发展中。这些模式在方位角波数,涡旋的位置(距旋转轴的距离)以及涡旋系统相对于腔的方位角漂移率方面有所不同。结果表明,芯差旋转改变了方位角速度分布,导致不稳定性阈值的变化。由于额外的方位角流动,两种情况下相同类型涡旋的漂移速度是不同的。研究了在各种不稳定性模式下,磁心差旋转对色散关系的影响。这些模式在方位角波数,涡旋的位置(距旋转轴的距离)以及涡旋系统相对于腔的方位角漂移率方面有所不同。结果表明,芯差旋转改变了方位角速度分布,导致不稳定性阈值的变化。由于额外的方位角流动,两种情况下相同类型涡旋的漂移速度是不同的。研究了在各种不稳定性模式下,磁心差旋转对色散关系的影响。这些模式在方位角波数,涡旋的位置(距旋转轴的距离)以及涡旋系统相对于腔的方位角漂移率方面有所不同。结果表明,芯差旋转改变了方位角速度分布,导致不稳定性阈值的变化。由于额外的方位角流动,两种情况下相同类型涡旋的漂移速度是不同的。研究了在各种不稳定性模式下,磁心差旋转对色散关系的影响。导致不稳定性阈值发生变化。由于额外的方位角流动,两种情况下相同类型涡旋的漂移速度是不同的。研究了在各种不稳定性模式下,磁心差旋转对色散关系的影响。导致不稳定性阈值发生变化。由于额外的方位角流动,两种情况下相同类型涡旋的漂移速度是不同的。已经研究了核心不均匀旋转对各种不稳定性模式下色散关系的影响。

更新日期:2020-06-22
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