粒子軸に垂直な磁気モーメントを有する強磁性針状粒子からなる非希釈コロイド分散系の磁気特性による負の粘度 : 平均場近似による粒子間相互作用を考慮した解析(流体工学,流体機械)

概要

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We have investigated the negative viscosity of a colloidal dispersion composed of ferromagnetic rod-like particles, which have a magnetic moment normal to the particle axis. We have here treated a simple shear flow problem to clarify the particle orientational distribution and rheological properties of such a semi-dense dispersion, under circumstances of an external magnetic field applied in the direction normal to the shear plane of a simple shear flow. In order to take into account magnetic interactions between particles, the mean field approximation has been adopted. The results obtained here are summarized as follows. Characteristic orientational properties of the particle cause negative viscosity, as in the previous study for a dilute dispersion. However, magnetic particle-particle interactions have a function to make such negative viscosity decrease, since the magnetic moment of the particle tends to align in the magnetic field direction more significantly with magnetic particle-particle interactions increasing.
社団法人日本機械学会の論文
2007-10-25