关键词: 纳米结构, 润湿性, 气泡核化, 两相流, 分子模拟

Abstract:

Molecular dynamics simulation was used to simulate the nucleation growth of liquid on a solid wall in a restricted nanochannel. The effect of solid wall wettability on liquid nucleation growth was studied and the mechanism of bubble nucleation was analyzed. The results showed that different wall wettability had a great influence on the growth of bubble nucleation. When the wall surface wettability was strong, a liquid film would be formed near the wall surface, which was different from the boiling in the pool. The fluid was homogeneously nucleated in the liquid film layer, and the bubble nucleation growth rate was faster. When the wall wettability was weak, the liquid underwent heterogeneous nucleation at the near wall surface, and the bubble nucleation growth rate was relatively slow. When the wall wettability was the weakest, a gas film was formed at the near wall surface, and heat was transferred to the fluid through the gas film. The heat transfer effect was not good and the liquid was hard to be nucleated. The reason for this phenomenon was that the wall surface was highly wet and a “solid-like” layer was formed at the near wall surface. Heat was transferred to the “solid-like” layer through the wall surface, and further transferred to the fluid in the channel through the “solid-like” layer. The effect of heat transfer was good. In addition, the thicker the “solid-like” layer, the better the heat transfer effect. When the wall wettability was weak, there was no “solid-like” layer near the wall surface, which would form a gas film to reduce the heat transfer effect and affected the fluid nucleation growth in the channel.

Key words: nanostructure, wettability, bubble nucleation, two-phase flow, molecular dynamics