Marangoni convection instability in a sessile droplet with low volatility on heated substrate
Marangoni convection instability in a sessile droplet with low volatility on heated substrate
复制标题
加热基底上低挥发性固着液滴的马兰戈尼对流不稳定性
DOI：
10.1016/j.ijthermalsci.2017.04.007
复制
发表时间：
2017-07-01
影响因子：
4.5
通讯作者：
Feng, Lin
中科院分区：
文献类型：
--
作者：
Shi, Wan-Yuan;Tang, Kai-Yi;Feng, Lin
为了研究受热基底上液滴的马兰戈尼对流，在较宽的马兰戈尼数范围内进行了一系列的三维数值模拟。采用低挥发性硅油，忽略蒸发的影响。由于液滴的曲面特性，使得贝纳德-马兰戈尼对流和热毛细对流在液滴内部可能同时存在。当Marangoni数较低时，流动是稳定的轴对称热毛细对流，而当Marangoni数较高时，流动变得不对称而失去稳定性，并发生Hopf分岔。随着Marangoni数的增加，振荡过渡对流、稳定Benard-Marangoni对流和不规则振荡Benard-Marangoni对流依次出现。描述了各种对流模式的特征，并确定了在大接触角范围内对流模式发生的临界Marangoni数。最有趣的现象之一是，在无底液滴中，bennard - marangoni对流细胞的形状是圆形的，这与平面层中经典的六边形对流细胞的形状不同。随着接触角的增大，对流不稳定发生的临界马兰戈尼数先减小后增大。稳态Benard-Marangoni对流的临界胞数在接触角小于15时仅为1，大于15度时急剧增加。通过实验对数值结果进行了定性验证。(C) 2017 Elsevier Masson SAS。版权所有。
In order to investigate Marangoni convection in a sessile droplet on heated substrate, a series of threedimensional numerical simulations are carried out in a wide range of Marangoni number. A low volatile silicone oil is adopted and the effect of evaporation is neglected. Benard-Marangoni convection and thermocapillary convection may coexist in droplet because of its curve surface. When Marangoni number is low the flow is steady axisymmetric thermocapillary convection whereas the flow becomes to be asymmetric and loses its stability and Hopf bifurcation occurs when Marangoni number high. The oscillatory transition convection, steady Benard-Marangoni convection and irregular oscillatory Benard-Marangoni convection appear in sequence with increasing Marangoni number. The characteristics of each kind of convection modes are described and the critical Marangoni numbers for the incipience of them are determined in a wide range of contact angles. One of the most interesting phenomenon is that the shape of the Benard-Marangoni convection cell in sessile droplet is circular, which is different from that of classical hexagonal cell in flat layer. With increasing contact angle, the critical Marangoni number for the onset of convection instabilities first decreases and then increases. Critical cell number of the steady Benard-Marangoni convection keeps on only one for contact angle less than 15 whereas it increases sharply after angle lager than 15 degrees. The numerical results are qualitatively verified by experiment. (C) 2017 Elsevier Masson SAS. All rights reserved.