Toro-Mendoza Jhoan, Rodriguez-Lopez Gieberth, Paredes-Altuve Oscar
Instituto Venezolano de Investigaciones Cientificas, Centro de Estudios Interdisciplinarios de la Fisica, Caracas, Venezuela.
Instituto Venezolano de Investigaciones Cientificas, Centro de Fisica, Caracas, Venezuela.
Phys Chem Chem Phys. 2017 Mar 29;19(13):9092-9095. doi: 10.1039/c6cp07442a.
Here, the effect of the elastic response of the surface on the translational diffusion coefficient of a partly submerged-in-water spherical Brownian particle is considered. The elastic nature of the surface, mediated by the surface tension, generates an additional dissipative mechanism. Therefore, the collisions at the surface contribute to the diffusion as the source of the driving force and the dissipation results from the combined action of both elastic reaction of the surface and viscous dissipation. However, it can be estimated that the surface elastic mechanism is several orders of magnitude greater than the viscous one. This simple yet physically plausible approach leads us to assume that the diffusion on the surface is proportional to a power of the number of collisions and, consequently, the dissipative mechanisms are proportional to an inverse power of it. The lowering in dimensionality from 3 (bulk) to 2 (surface) also contributes to the decrease of diffusion. This model allows the reproduction of the reported experimental values of the surface/bulk dissipative force ratio. Additionally, we also compared the traditional viscous approach with other theoretical hydrodynamic treatments of the problem, which drastically failed to explain the experiments.
在此，考虑了表面的弹性响应对部分浸入水中的球形布朗粒子平动扩散系数的影响。由表面张力介导的表面弹性性质产生了一种额外的耗散机制。因此，表面处的碰撞作为驱动力的来源对扩散有贡献，而耗散则是表面弹性反应和粘性耗散共同作用的结果。然而，可以估计表面弹性机制比粘性机制大几个数量级。这种简单但物理上合理的方法使我们假设表面上的扩散与碰撞次数的幂成正比，因此，耗散机制与之成反比幂关系。维度从三维（体相）降至二维（表面）也导致扩散减小。该模型能够重现所报道的表面/体相耗散力比的实验值。此外，我们还将传统的粘性方法与该问题的其他理论流体动力学处理方法进行了比较，结果发现这些方法根本无法解释实验现象。
