Wheeler Daniel, Warren James A, Boettinger William J
Metallurgy Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 Nov;82(5 Pt 1):051601. doi: 10.1103/PhysRevE.82.051601. Epub 2010 Nov 9.
Recent experimental studies of molten metal droplets wetting high-temperature reactive substrates have established that the majority of triple-line motion occurs when inertial effects are dominant. In light of these studies, this paper investigates wetting and spreading on reactive substrates when inertial effects are dominant using a thermodynamically derived diffuse interface model of a binary three-phase material. The liquid-vapor transition is modeled using a van der Waals diffuse interface approach, while the solid-fluid transition is modeled using a phase field approach. The results from the simulations demonstrate an O(t(-1/2)) spreading rate during the inertial regime and oscillations in the triple-line position when the metal droplet transitions from inertial to diffusive spreading. It is found that the spreading extent is reduced by enhancing dissolution by manipulating the initial liquid composition. The results from the model exhibit good qualitative and quantitative agreement with a number of recent experimental studies of high-temperature droplet spreading, particularly experiments of copper droplets spreading on silicon substrates. Analysis of the numerical data from the model suggests that the extent and rate of spreading are regulated by the spreading coefficient calculated from a force balance based on a plausible definition of the instantaneous interface energies. A number of contemporary publications have discussed the likely dissipation mechanism in spreading droplets. Thus, we examine the dissipation mechanism using the entropy-production field and determine that dissipation primarily occurs in the locality of the triple-line region during the inertial stage but extends along the solid-liquid interface region during the diffusive stage.
最近关于熔融金属液滴润湿高温反应性基底的实验研究表明，当惯性效应占主导时，大部分三线运动就会发生。鉴于这些研究，本文使用二元三相材料的热力学推导扩散界面模型，研究了惯性效应占主导时反应性基底上的润湿和铺展情况。液 - 气转变采用范德华扩散界面方法进行建模，而固 - 液转变则采用相场方法进行建模。模拟结果表明，在惯性阶段铺展速率为O(t(-1/2))，并且当金属液滴从惯性铺展转变为扩散铺展时，三线位置会出现振荡。研究发现，通过控制初始液体成分增强溶解作用会降低铺展程度。该模型的结果与近期一些关于高温液滴铺展的实验研究在定性和定量上都有很好的一致性，特别是铜液滴在硅基底上铺展的实验。对该模型数值数据的分析表明，铺展的程度和速率由基于瞬时界面能的合理定义通过力平衡计算得到的铺展系数来调节。许多当代出版物都讨论了铺展液滴中可能的耗散机制。因此，我们使用熵产生场来研究耗散机制，并确定耗散主要发生在惯性阶段三线区域的局部，但在扩散阶段会沿着固 - 液界面区域扩展。
