Zhou Yi, Zhu Changxing, Bian Kun, Yang Mingyuan, Yang Chun
Key Laboratory of High Performance Ship Technology, Ministry of Education, School of Energy and Power Engineering, Wuhan University of Technology, Wuhan, P. R. China.
School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, P. R. China.
Electrophoresis. 2021 Nov;42(21-22):2391-2400. doi: 10.1002/elps.202100127. Epub 2021 Aug 7.
Thermophoresis of charged spheroids has been widely applied in biology and medical science. In this work, we report an analysis of the anisotropic thermophoresis of diluted spheroidal colloids in aqueous media for extremely thin EDL cases. Under the boundary layer approximation, we formulate the thermophoretic velocity, the thermophoretic force, and the thermodiffusion coefficient of a randomly dispersed spheroid. The parametric studies show that under the aforementioned conditions, the thermophoresis is anisotropic and its thermodiffusion coefficient should be considered as a vector, D . The thermodiffusion coefficient values and directions of D are strongly related to the aspect ratio and the angle θ between the externally applied temperature gradient and the particle's axis of revolution: The increasing aspect ratio enlarges the thermodiffusion coefficient value D of prolate (oblate) spheroids to a constant value when θ < 60° (θ > 45°), and it reduces D of prolate (oblate) spheroids to a constant value when θ > 60° (θ < 45°). The thermodiffusion coefficient direction of both prolate and oblate spheroids deviates slightly from -∇T for a small aspect ratio, and such deviation becomes serious for a large aspect ratio.
带电球体的热泳现象已在生物学和医学领域得到广泛应用。在这项工作中，我们报告了在极薄双电层情况下，对水性介质中稀释的球状胶体的各向异性热泳现象的分析。在边界层近似下，我们推导了随机分散球体的热泳速度、热泳力和热扩散系数。参数研究表明，在上述条件下，热泳是各向异性的，其热扩散系数应被视为一个矢量D。热扩散系数D的值和方向与纵横比以及外加温度梯度与粒子旋转轴之间的夹角θ密切相关：当θ < 60°（θ > 45°）时，纵横比的增加会使长（扁）球体的热扩散系数值D增大到一个恒定值；而当θ > 60°（θ < 45°）时，纵横比的增加会使长（扁）球体的热扩散系数值D减小到一个恒定值。对于小纵横比的长球体和扁球体，其热扩散系数方向均略微偏离-∇T，而对于大纵横比，这种偏离会变得很明显。
