Abstract Heat and mass transfer in a bilayer system of viscous incompressible liquids with interfaces have been studied theoretically and experimentally. Thermocapillary convection and interface deformations have been induced by an intense thermal exposure on the free boundary due to the action of a laser beam. The evolution of the interfaces and liquid behavior have been experimentally investigated. The static profile of the liquid – liquid interface and free surface have been measured using the laser-sheet technique. The scheme of the experiment and parameters of the physical system have been presented. The theoretical study of the system dynamics includes the development of a correct mathematical model in the framework of continuum mechanics and creation of an effective numerical algorithm, validated with the help of new experimental results. An outline of the numerical method has been given. The proposed approach allows one to describe the characteristics of the arising flows, to predict the shape of thermocapillary deformations of the liquid interfaces, and to analyze the interaction of the thermal gravitational and thermocapillary convection. The mechanisms causing the occurrence of the decaying oscillations that were first discovered by the authors have been discussed. The results of the numerical study for a two-layer system of the “silicone oil – glycerin” type are in good agreement with the experimental data, and enable to estimate the influence of the upper layer thickness on the features of fluid motion and to forecast the rupture time of the top liquid under local heating at the free boundary. The rupture time depends on the rate at which the threshold temperature difference in the top layer sets in. For systems with relatively large thickness of the upper layer the appearance of a stable profile of the thermocapillary flexure on the free surface without layer breakdown is characteristic.

中文翻译：

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激光束加热下两层液体系统的热毛细管变形

摘要 对具有界面的粘性不可压缩液体双层系统中的传热传质进行了理论和实验研究。由于激光束的作用，自由边界上的强烈热暴露引起了热毛细对流和界面变形。已经通过实验研究了界面和液体行为的演变。液体 - 液体界面和自由表面的静态轮廓已使用激光片技术测量。给出了实验方案和物理系统参数。系统动力学的理论研究包括在连续介质力学框架内开发正确的数学模型和创建有效的数值算法，并在新实验结果的帮助下进行验证。已经给出了数值方法的概要。所提出的方法允许人们描述产生的流动的特征，预测液体界面的热毛细变形的形状，并分析热重力和热毛细对流的相互作用。已经讨论了引起作者首次发现的衰减振荡发生的机制。“硅油-甘油”型两层体系的数值研究结果与实验数据吻合较好，可以估计上层厚度对流体运动特征的影响并进行预测。自由边界处局部加热下顶部液体的破裂时间。