FERROHYDRODYNAMIC PUMPING IN SPATIALLY UNIFORM SINUSOIDALLY TIME-VARYING MAGNETIC-FIELDS
FERROHYDRODYNAMIC PUMPING IN SPATIALLY UNIFORM SINUSOIDALLY TIME-VARYING MAGNETIC-FIELDS
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DOI：
10.1016/0304-8853(95)00363-0
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发表时间：
1995-08-01
影响因子：
2.7
通讯作者：
GREER, DR
中科院分区：
文献类型：
--
作者：
ZAHN, M;GREER, DR
过去的工作分析了空间非均匀行波磁场驱动的平面管道中的铁磁流体泵送。在这里，我们研究一个更简单的情况下，施加的磁场沿着和横向的管道轴是空间均匀的，并随时间正弦变化;在均匀磁场的磁化特性取决于粒子自旋，但不取决于流体的速度。沿着管道轴线的磁化力密度沿着为零，而磁矩密度为非零，因为M和H由于磁弛豫时间常数以及由于空间变化的粒子自旋而不共线。控制线性和角动量守恒方程的数值积分，以解决零和非零自旋粘度作为磁场强度的函数，相位，频率和方向沿着和横向的管道轴的流动和自旋速度分布，并作为压力梯度沿着管道，涡流粘度，动力粘度和铁磁流体磁化率的函数。简单的极限情况下的解析解也给出了包括有效粘度，取决于磁场强度，可以是零或负的。
Past work has analyzed ferrofluid pumping in a planar duct driven by spatially non-uniform traveling wave magnetic fields. Here we examine a much simpler case where the applied magnetic fields along and transverse to the duct axis are spatially uniform and varying sinusoidally with time; In the uniform magnetic field the magnetization characteristic depends on particle spin but does not depend on fluid velocity. The magnetization force density along the duct axis is zero while the magnetic torque density is non-zero as M and H are not collinear due to a magnetic relaxation time constant as well as due to spatially varying particle spin. The governing linear and angular momentum conservation equations are numerically integrated to solve for flow and spin velocity distributions for zero and non-zero spin viscosities as a function of magnetic field strength, phase, frequency, and direction along and transverse to the duct axis, and as a function of pressure gradient along the duct, vortex viscosity, dynamic viscosity, and ferrofluid magnetic susceptibility. Analytical solutions for simple limiting cases are also given including an effective viscosity that depends on magnetic field strength which can be made zero or negative.