不同润湿表面液体沸腾的分子动力学模拟

Molecular dynamics simulation of liquid boiling on different wetting surfaces

采用分子动力学方法研究纳米尺度下液氩在过热基板上的沸腾过程。通过调节固液间相互作用的方式改变壁面润湿性,模拟并分析了壁面润湿性对沸腾过程中能量传递和液体运动情况的影响。结果表明:不同润湿性表面均会发生固液分离的现象,但是固体表面附近吸附的氩原子数密度随润湿性增强而增大;润湿性较强时,液体的能量上升快,热通量高,液体内部温度梯度大,发生固液分离时间早,系统中氩的温度和能量低,上升过程中液氩密度、厚度变化小;润湿性较弱时,液体的能量上升慢,热通量小,液体内部温度梯度小,发生固液分离时间延后,系统中氩的温度、能量更高,上升过程中液氩密度、厚度变化较大。下部气体压力整体上大于上部气体压力,发生固液分离时润湿性越强的表面上液体上下压差越大,首次上升过程能达到的高度越高,所需时间越短。

The boiling process of liquid argon on superheated substrates at nanoscale was investigated by molecular dynamics simulations.The wall wettability was changed by changing the way of solid-liquid interaction.The effects of wall wettability on energy transfer and liquid motion during boiling were simulated and analyzed.The results showed that solid-liquid separation occurs on different wettable surfaces.As the wettability increases,the number density of argon atoms adsorbed near the solid surface increases.When the wettability is strong,the energy of the liquid rises faster.The heat flux is greater and the temperature gradient inside the liquid is larger.The solid-liquid separation phenomenon occurs earlier,and the temperature and energy of argon in the system are lower.The density and thickness of the liquid change less during the ascent.When the wettability is weak,the energy of the liquid rises more slowly.The heat flux density is smaller,and the temperature gradient inside the liquid is smaller.The solid-liquid separation phenomenon takes more time,and the temperature and energy of argon in the system are higher.The density and thickness of the liquid change more significantly during the ascent.The lower gas pressure is generally greater than the upper gas pressure.When solid-liquid separation occurs,the pressure difference between the liquid on the surface with strong wettability is more obvious,and the height of the first ascent process can reach a higher height and take less time.