沸腾过程的格子Boltzmann方法模拟

Simulation of Boiling Process with Lattice Boltzmann Method

提出了一种新的描述气液相变过程的格子Boltzmann理论模型,并利用该模型对液化和蒸发过程进行了模拟.对液化过程的计算结果表明,气相的体积分数、液相和气相的密度与理论解的最大相对误差分别为1.18%、0.23%、0.32%,而蒸发过程的计算结果相应的最大相对误差分别为0.08%、0.48%、0.20%,较前人研究的结果更接近理论解.为进一步验证该模型模拟复杂相变问题的可行性,利用该模型对池内沸腾和垂直管道中的流动沸腾现象进行了模拟,观察到气泡随时间变化不断长大,气泡受浮升力的影响脱离壁面,以及气泡在液相中上升时发生碰撞、聚合等现象.

A new lattice Boltzmann model is proposed to describe liquid-vapor phase transitions, and then the simulation on condensation and vaporization is performed. The simulation results show that the maximum relative error of the volume fraction of vapor phase, the liquid phase den- sity, and the vapor phase density is 1.18%, 0. 23%, and 0. 32%, respectively, for the process of condensation and 0.08%, 0. 48%, and 0. 20%, respectively, for the process of vaporization. Compared with previous results, the present results are more close to analytical solutions. In order to further confirm the feasibility to simulate complicated phase transitions with the present model, the simulation on pool boiling and boiling flow in a vertical pipe is conducted. It is observed from the results that small and spherical bubbles grow near the wall and rise due to buoyancy, and collisions and coalescences of the bubbles occur occasionally while the bubbles rise.