Thermocapillary flow and rupture in films of molten metal on a substrate
Thermocapillary flow and rupture in films of molten metal on a substrate
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基材上熔融金属薄膜的热毛细管流动和破裂
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
D. A. Willis
中科院分区：
文献类型：
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作者：
V. Ajaev;D. A. Willis
我们考虑了高斯激光辐照金属熔体薄膜中的流体流动问题。由于不均匀加热引起的表面张力梯度会导致熔融液体离开受照射区域的中心，导致在衬底上形成干燥区。在假定激光半径与膜厚之比较大的情况下，建立了流动的数学模型。该模型扩展了标准的润滑型分析，包括蒸发通量对局部界面温度的高度非线性依赖、衬底中的非稳态热传导以及由于金属中自由电子动能的不平衡贡献而产生的正分离压力。后者与薄膜厚度的平方成反比。我们认为热毛细管应力是从辐照区域快速去除液态金属的主要机制。该过程的特征时间以及熔化区表面的形状与实验结果相吻合。
We consider fluid flow in thin films of molten metal resulting from irradiation by a Gaussian laser beam. Surface tension gradients due to nonuniform heating induce a flow of the molten liquid away from the center of the irradiated area, leading to formation of dry areas on the substrate. We develop a mathematical model of the flow under the assumption of the large ratio of laser beam radius to film thickness. The model extends the standard lubrication-type analysis to include the highly nonlinear dependence of evaporative flux on local interfacial temperature, unsteady heat conduction in the substrate, and positive disjoining pressure due to unbalanced contributions from the kinetic energy of free electrons in the metal. The latter is proportional to the inverse square of the film thickness. We identify thermocapillary stresses as the main mechanism of rapid removal of liquid metal from the irradiated area. Characteristic times of the process, as well as shapes of the molten region surface, agree with ex...