Magnetorheological Fluid Structure in a Pulsed Magnetic Field
Magnetorheological Fluid Structure in a Pulsed Magnetic Field
复制标题
脉冲磁场中的磁流变流体结构
DOI：
--
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
A. Gast
中科院分区：
文献类型：
--
作者：
J. Promislow;A. Gast
通过光学显微镜研究单分散可磁化油滴乳液的脉冲场结构。通过允许液滴在场关闭状态下扩散，脉冲场可以通过结构重排将能量最小化。对于磁化率 χ = 2.2 且半径 a ≥ 0.32 μm 的液滴，我们发现在脉冲磁场的响应下会发生重排成椭圆体聚集体。椭圆体末端由低脉冲频率下的链状突起和高脉冲频率下的圆锥形尖峰组成。圆锥形尖峰似乎在能量上是有利的，但由于在场关闭状态下液滴的扩散距离很大，所以不能在低脉冲频率下形成。在强场中，椭球体的偏心率不随场强变化，但在弱场中，我们发现，随着场强的降低，椭球体变得更加拉长。弱场中的这种伸长与更稀的聚集体和 g 的形成同时发生。
The pulsed-field structure of an emulsion of monodisperse, magnetizable oil droplets is investigated via optical microscopy. By permitting droplet diffusion in the field-off state, a pulsed field allows minimization of energy through structural rearrangement. For droplets with a magnetic susceptibility of χ = 2.2 and radius a ≥ 0.32 μm, we find that rearrangement into ellipsoidal aggregates occurs in response to a pulsed magnetic field. The ellipsoid ends are composed of chainlike projections at low pulse frequencies and conical spikes at high pulse frequencies. The conical spikes appear to be energetically favored but cannot form at low pulse frequencies due to the large diffusion distance of the droplets in the field-off state. The eccentricity of the ellipsoids is invariant with field strength in strong fields, but in weak fields we find that the ellipsoids become more elongated as the field strength is lowered. This elongation in weak fields coincides with the formation of more dilute aggregates and g...