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基于不可压格子玻尔兹曼气-液两相流模型, 建立了一个新的非牛顿幂律流体气-液两相流模型, 并采用该模型研究了多孔介质内牛顿气体驱替非牛顿幂律流体液体的驱替问题, 主要探究了 Ca数、动力黏度比 M、固体表面润湿性 θ、多孔结构几何类型及幂律指数 n对驱替过程的影响. 研究发现: 不论被驱替液体为剪切变稀流体、牛顿流体还是剪切变稠流体都有随着 Ca数增加, 驱替速度越快, 指进现象越明显, 驱替效率越低. 然而对于不同的幂率指数 n, 驱替效率随 Ca数的增加而减小的速率不同: n越大驱替效率随着 Ca数增加而减小的速率越慢. 另一方面, 随着黏性比 M增加, 驱替效率减小, 且幂律指数 n越小, M对驱替效率的影响越大. 此外, 固体表面接触角 θ对驱替过程的影响也和被驱替流体的幂率指数 n相关, 虽然对于 n> 1和 n< 1的情况都有随着多孔介质固体表面接触角 θ增加, 驱替过程受到的阻力越小, 指进越来越不明显, 驱替完成时间和驱替效率增加, 然而当 n> 1时, 随着 n的增加, 接触角对驱替过程的影响越来越小. 还研究了孔隙率相同的情况下, 孔隙几何类型不同时的驱替过程, 从数值结果可以发现与多孔结构为圆形和方形障碍物相比, 当多孔结构的几何类型为三角形时, 指进现象最明显, 驱替效率最低.
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关键词:
- 幂律两相流体/
- 格子Boltzmann模型/
- 不混溶驱替/
- 多孔介质
A new incompressible gas-liquid two-phase flow model for non-Newtonian power-law fluid is proposed based on an incompressible lattice Boltzmann model. And the fundamental physical mechanism of Newtonian fluid displacing non-Newtonian power-law fluid liquid in porous medium is studied by using the proposed model. The effects of capillary number Ca, dynamic viscosity ratio M, surface wettability θ, porous medium geometry, and power law index non the displacement process are investigated. The comprehensive results show that with the increase of capillary number, the displacement process turns faster, the fingering phenomenon becomes more obvious and the displacement efficiency decreases. However, for different values of power-law index n, the effects of the Caon the displacement process have some differences. Specially, the decrease rate of displacement efficiency becomes slow if the displaced fluid is shear thickening fluid as compared with that if the displaced fluid is shear thinning fluid. On the other hand, the displacement efficiency decreases as dynamic viscosity ratio Mincreases. And the effect of the viscosity ratio on the displacement process becomes more obvious for the low value of the power-law index n. Moreover, the effect of the surface wettability of the porous medium on the displacement process is also related to the size of the power-law index. With the increase of the contact angle of the porous medium, the fingering phenomenon turns less obvious, and the displacement efficiency increases. However, with the increase of power-law index n, the influence of the contact angle on the displacement process decreases. Besides, the displacement processes with different geometric types of the porous media are also studied in the work. The results show that comparing with the case of porous medium denoted by circle shape and square shape, the fingering phenomenon obtained by the case of triangular shape is most obvious, and the displacement efficiency is lowest.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] -
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