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The stability characteristics of an ultra-thin layer of a viscous liquid flowing down a cylindrical fibre are investigated
by a linear theory. The film with the thickness less than 100 nm is driven by an external force and under the influence of
the van der Waals forces. The results show that, when the relative film thickness decreases, the curvature of the fibre depresses
the development of the linear perturbations, whereas the van der Waals forces promote the instabilities. This competition
results in a non-monotonous dependence of the growth rate on the relative film thickness. The critical curves are also obtained
to describe the transition from the absolute instability to the convective instability, indicating that the van der Waals
forces can enlarge the absolutely unstable region. Furthermore, the surface tension can cause the development of the absolute
instability, whereas the external force has an opposite effect. 相似文献
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用渐近方法和相场数值模拟分别研究了球状晶体和柱状晶体凝固过程中,固液界面表面张力随温度的变化对界面运动的影响.结果表明Marangoni效应将增大临界晶核半径,减缓界面运动速度.在静止熔体中,枝晶尖端生长速度随Marangoni数线性下降.渐近展开和相场模拟得到的结果定性是一致的. 相似文献
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The asymptotic method and phase field simulation are applied to study the influences of variation of the surface tension with temperature on the movements of solid-liquid interfaces in the solidification process of spherical and cylindrical nuclei, respectively. Results indicate that Marangoni effect will increase the critical nucleation radius, slow up the movement of interface. The tip speed of dendrite decreases linearly with Marangoni number for melt without convection. The results of phase field simulation are qualitatively in accord with that of asymptotic method. 相似文献
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