基于格子Boltzmann方法的饱和土壤渗流与传热数值模拟

Numerical simulation of seepage and heat transfer in saturated soils based on lattice Boltzmann method

中文关键词: 多孔介质  格子Boltzmann方法  孔隙尺度  渗流与传热

英文关键词: porous media  lattice Boltzmann method  pore scale  seepage and heat transfer

中文摘要:

      本文利用随机多孔介质生成算法重构了与真实土壤外貌相近的多孔介质几何结构。通过引入不可压耦合双分布格子Boltzmann模型（lattice Boltzmann model ,LBM）对孔隙尺度下单相饱和土壤渗流和传热进行了模拟。着重讨论了不同渗流压差、孔隙率、土壤固体颗粒尺寸分布对流动与传热的影响。结果表明：土壤渗流速度与渗流压差呈线性单调递增关系，平均温度随渗流压差增加而增大，但温升速率逐渐减缓;当孔隙率增大时，渗流速度增加，且当孔隙率大于0.58时，对流换热作用迅速增强，土壤温升速率显著加快;对于相同孔隙率，当土壤固相颗粒尺寸较大时，流动出现典型优先流效应;随着土壤固相颗粒尺寸减小，土壤温度变化逐渐趋于平缓，平均温度降低。

英文摘要:

      A random generation growth method was introduced to reconstruct the microstructure of soil. The geometry of reconstruction was similar to real pore-scale structure of soil. A numerical study was then performed for simulation of pore-scale single phase saturated soil seepage and heat transfer process by lattice Boltzmann model (LBM). Effects of different seepage pressure difference, porosity and particle size of porous media on flow and heat transfer were analyzed emphatically. The results indicate that the seepage velocity and average temperature of soil are positive correlation between the seepage pressure difference, while temperature rise rate slows down gradually. With the porosity increases, the seepage velocity increases spontaneously , and when the porosity of soil is higher than 0.58, the effects of convective heat transfer and the temperature rise rate are rapidly increasing . For the same porosity, when the soil particle size is larger, the phenomenon of typical preferential flow occurs. With the reduce of soil particle size, the temperature of soil changes slowly and average value decreases accordingly.