Direct numerical simulations for non-Newtonian rheology of concentrated particle dispersions.
Direct numerical simulations for non-Newtonian rheology of concentrated particle dispersions.
复制标题
浓缩颗粒分散体的非牛顿流变学的直接数值模拟。
DOI：
10.1103/physreve.80.061402
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
R. Yamamoto
中科院分区：
文献类型：
--
作者：
T. Iwashita;R. Yamamoto
采用直接数值模拟方法研究了球形颗粒单分散集中分散体系的非牛顿行为，该方法精确地考虑了流体动力学相互作用和温度波动。在三个方向上具有周期性边界条件的稳态剪切流下进行模拟。在0.31至0.56的体积分数下计算分散体的表观剪切粘度。在高体积分数下清楚地观察到剪切稀化行为。低和高的极限粘度，然后估计从表观粘度拟合这些数据到一个半经验公式。此外，研究了布朗粒子在浓分散体中的短时运动，流体惯性对布朗粒子的短时运动起着重要的作用。在几个不同的Peclet数和体积分数的涡度方向上的均方位移进行监测，以便从均方位移的长时间行为确定颗粒扩散系数。最后，非牛顿粘度的分散体和分散的布朗粒子的结构松弛之间的关系进行了检查。
The non-Newtonian behavior of a monodisperse concentrated dispersion of spherical particles was investigated using a direct numerical simulation method, which takes into account hydrodynamic interactions and thermal fluctuations accurately. Simulations were performed under steady shear flow with periodic boundary conditions in the three directions. The apparent shear viscosity of the dispersions was calculated at volume fractions ranging from 0.31 to 0.56. Shear-thinning behavior was clearly observed at high volume fractions. The low- and high-limiting viscosities were then estimated from the apparent viscosity by fitting these data into a semiempirical formula. Furthermore, the short-time motions were examined for Brownian particles fluctuating in concentrated dispersions, for which the fluid inertia plays an important role. The mean square displacement was monitored in the vorticity direction at several different Peclet numbers and volume fractions so that the particle diffusion coefficient is determined from the long-time behavior of the mean square displacement. Finally, the relationship between the non-Newtonian viscosity of the dispersions and the structural relaxation of the dispersed Brownian particles is examined.