基于多松弛LBM的固液熔融过程模拟研究

Researches on Solid-liquid Melting Process Based on MRT-LBM Simulation

固液熔融过程具有温度/体积变化小、潜热释放/吸收量大的特点,在工程技术中具有重要的应用。为了更好的利用固液熔融过程进行储能,本文采用具有多松弛时间碰撞模型的双分布函数格子Boltzmann方法对方腔内固液熔融过程进行数值模拟,探究Rayleigh数(Ra)和Stefan数(Ste)对相变熔融过程的影响,并对相应无量纲结果进行展示和分析。结果表明,Ra数的增加不仅有利于对流起始时间的提前,还有利于速度涡的形成。而Ste数会使对流起始时间略有增加,但对速度涡的形成没有明显影响。此外,Ra数或Ste数的增加均有利于缩短完全熔融时间。

Due to the characteristics of little temperature/volume change and strong latent heat release/absorption,the solid-liquid melting process is extensively utilized in engineering technologies.In order to better utilize the solid-liquid melting process for energy storage,based on double multiple relaxation time lattice Boltzmann method,the solid-liquid melting process in the square cavity is numerically investigated in this work.The effects of different Rayleigh numbers(Ra)and Stefan numbers(Ste)on the melting process are studied,and the corresponding dimensionless results are presented.The findings show that an increase in Ra number is beneficial for the formation of velocity vortices as well as for causing the convection to begin earlier.The Ste number has no noticeable effect on the formation of velocity vortices,but it can also bring the onset time of convection forward.Additionally,a decrease in Ra or Ste numbers is advantageous for accelerating the melting process.