Sullivan P, Dockar D, Pillai R
Department of Earth Sciences, Durham University, Science Labs, Durham DH1 3LE, United Kingdom.
Institute for Multiscale Thermofluids, University of Edinburgh, Edinburgh EH9 3FB, United Kingdom.
J Chem Phys. 2025 May 14;162(18). doi: 10.1063/5.0259208.
Understanding the mechanisms underlying vapor bubble nucleation on solid surfaces is critical for multiple scientific and engineering applications, such as two-phase thermal management systems and turbomachinery, among others. While classical nucleation theory (CNT) explains how surface wettability influences nucleation by modifying the free energy barrier for smooth surfaces, the interplay between nanoscale surface roughness and wettability for rough surfaces remains less clear. Using molecular dynamics simulations, this study demonstrates that CNT can accurately describe wettability effects on nucleation. In addition, we show how surface cavities can create active nucleation sites without requiring trapped gases. This occurs through spontaneous dewetting of cavities at elevated temperatures, which reduces the nucleation barrier. Our results reveal that cavity-induced nucleation enhancement depends on both wettability and geometry, with dewetting promoting nucleation on lyophobic surfaces and rewetting neutralizing this effect for more lyophilic surfaces. These findings provide insights for designing surfaces to either enhance or suppress bubble nucleation.
了解固体表面上蒸汽泡核化的潜在机制对于多种科学和工程应用至关重要，例如两相热管理系统和涡轮机械等。虽然经典成核理论（CNT）解释了表面润湿性如何通过改变光滑表面的自由能垒来影响成核，但纳米级表面粗糙度与粗糙表面润湿性之间的相互作用仍不太清楚。本研究通过分子动力学模拟表明，CNT可以准确描述润湿性对成核的影响。此外，我们展示了表面空洞如何在不需要截留气体的情况下产生活性成核位点。这是通过高温下空洞的自发去湿实现的，这降低了成核势垒。我们的结果表明，空洞诱导的成核增强取决于润湿性和几何形状，去湿促进疏液表面上的成核，而再湿则使亲液性更强的表面的这种效应中和。这些发现为设计增强或抑制气泡成核的表面提供了见解。
