Ferromagnetic rotating Couette flow: the role of magnetic viscosity
Ferromagnetic rotating Couette flow: the role of magnetic viscosity
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DOI：
10.1017/s0022112001006590
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发表时间：
2002-02-25
影响因子：
3.7
通讯作者：
Hart, JE
中科院分区：
文献类型：
--
作者：
Hart, JE
建立了周期磁体阵列产生的磁场作用下旋转平面磁流体Couette流的理论。所分析的系统包含相当大的横向磁浮力，或称磁重力，使得该构型可用于连通几何形状的分层剪切流的实验研究。然而，磁堆的磁场矢量场的空间变化通过流动涡量对悬浮中颗粒取向的作用而导致磁致波浪流。基本的旋转Couette流动不稳定性也可能受到相同机制的影响，这有时被称为旋转粘性或‘磁性粘性’。理论计算表明，在预期的实验条件下，直接激发的波状流一般都很小，除非它们与Couette流的自然线性不稳定性共振。为了预测这些情况下的行为，进行了弱非线性分析。对于典型的实验室实现，磁效应将旋转Couette流的基本滚转不稳定性稳定约10%。
A theory is constructed for rotating plane Couette flow of ferrofluid that is subject to the field generated by a periodic array of magnets. The system that is analysed contains a substantial lateral magnetic buoyancy, or magnetic gravity, allowing the configuration to be used in experimental studies of stratified shear flows in a connected geometry.However, the spatial variation of the magnetic vector field of the magnet stack leads to magnetically generated wavy flows via the action of flow vorticity on the particle orientation in the suspension. The basic rotating Couette flow instabilities may also be affected by the same mechanism, which is sometimes referred to as rotational or 'magnetic viscosity'. Theoretical calculations show that the directly excited wavy flows are generally small, for anticipated experimental conditions, except when they resonate with the natural linear instabilities of the Couette flow. A weakly nonlinear analysis is carried out in order to predict the behaviour in these cases. Magnetic effects stabilize the fundamental roll instability of rotating Couette flow by about 10% for a typical laboratory realization.