Arango-Restrepo Andrés, Rubi J Miguel
Departament de Física de la Matéria Condensada, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647, 08028, Barcelona, Spain.
Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Barcelona, Spain.
Eur Phys J E Soft Matter. 2019 May 14;42(5):55. doi: 10.1140/epje/i2019-11822-y.
We compute the Soret coefficient for a particle moving through a fluid subjected to a temperature gradient. The viscosity and thermal conductivity of the particle are in general different from those of the solvent and its surface tension may depend on temperature. We find that the Soret coefficient depends linearly on the derivative of the surface tension with respect to temperature and decreases in accordance with the ratios between viscosities and thermal conductivities of particle and solvent. Additionally, the Soret coefficient also depends on a parameter which gives the ratio between Marangoni and shear stresses, a dependence which results from the local stresses inducing a heat flux along the particle surface. Our results are compared to those obtained by using the Stokes value for the mobility in the calculation of the Soret coefficient and in the estimation of the radius of the particle. We show cases in which these differences may be important. The new expression of the Soret coefficient can systematically be used for a more accurate study of thermophoresis.
我们计算了一个在存在温度梯度的流体中移动的粒子的索雷特系数。粒子的粘度和热导率通常与溶剂不同，并且其表面张力可能取决于温度。我们发现，索雷特系数与表面张力相对于温度的导数呈线性关系，并根据粒子与溶剂的粘度和热导率之比而减小。此外，索雷特系数还取决于一个给出马兰戈尼应力与剪切应力之比的参数，这种依赖性源于局部应力在粒子表面诱导热通量。我们将我们的结果与在索雷特系数计算和粒子半径估计中使用斯托克斯迁移率值所获得的结果进行了比较。我们展示了这些差异可能很重要的情况。索雷特系数的新表达式可系统地用于更精确地研究热泳现象。
