基于格子Boltzmann方法的毛细管相变流动模拟

Simulation of capillary phase transition flow based on lattice Boltzmann method

通过将大密度比两相流的自由能模型与格子热模型耦合建立一种新的描述气液相变的非等温格子Boltzmann模型,模拟研究毛细管内节流相变过程.结果表明,管内压降是驱动毛细管流动相变的重要因素.同时发现,气液两相间存在高温区,说明相变过程中靠近界面的液体可以不断地从高温处吸收热量,最后完全蒸发为气体.在速度分布上,模拟结果表明,管中心区域气体的速度远大于周围液体的速度.通过格子Boltzmann方法,从更细微的角度解释了毛细管相变机理.

A new non isothermal lattice Boltzmann model describing the phase transition of gas and liquid was established by coupling the free energy model of large density two phase flow with the lattice thermal model to simulate the process of internal throttling in capillary tube. Simulation results show that the pressure drop in the tube is an important factor to drive the capillary flow phase transition. At the same time, it is found that there is a high temperature zone between the two phases of the gas and liquid, which indicates that the liquid closing to the interface can absorb heat from the high temperature area continually in the process of phase transition until it evaporates into gas completely. Simulation results show that the velocity of the gas in the central area is much higher than that of the liquid around. The mechanism of capillary phase transition is explained in a more subtle way by the Lattice Boltzmann method.