Particle-resolved, three-dimensional, time-dependent simulations of rigid and flexible cylinders fluidized by a liquid flow in fully periodic domains have been performed by means of the lattice-Boltzmann method supplemented with immersed boundaries. The solids volume fraction ranges from 0.10 to 0.48 and the length-over-diameter aspect ratio of the cylinders from 4 to 12. The bending stiffness of the cylinders is the third major input parameter. The resulting Reynolds numbers based on the average slip velocity of the cylinders and their equivalent diameter range from 6 to 70. It is shown that increasing the flexibility—that is, decreasing the bending stiffness—reduces the Reynolds number, an effect that is most pronounced for low solids volume fractions and long cylinders. As for rigid cylinders, the distribution of the orientation relative to the direction of gravity of the flexible cylinders is a pronounced function of the solids volume fraction and the aspect ratio. Flexibility tends to somewhat randomize the orientation distribution, which could explain the effect of flexibility on the slip velocity and thus the Reynolds number.

中文翻译：

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刚性和柔性纤维液体流化的粒子分辨模拟

由完全周期域中的液体流流化的刚性和柔性圆柱体的粒子分辨、三维、时间相关模拟已通过补充浸入边界的格子-玻尔兹曼方法进行。固体体积分数的范围为 0.10 到 0.48，圆柱体的长径比为 4 到 12。圆柱体的抗弯刚度是第三个主要输入参数。基于圆柱体的平均滑移速度及其等效直径的所得雷诺数范围为 6 到 70。 结果表明，增加柔韧性（即降低弯曲刚度）会降低雷诺数，这种效果最为显着用于低固体体积分数和长圆柱体。对于刚性圆柱，相对于柔性圆柱体重力方向的取向分布是固体体积分数和纵横比的显着函数。柔韧性往往会使取向分布随机化，这可以解释柔韧性对滑移速度的影响，从而解释雷诺数。