Numerical investigation of dilute suspensions of rigid rods in power-law fluids
Numerical investigation of dilute suspensions of rigid rods in power-law fluids
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DOI：
10.1016/j.jnnfm.2020.104280
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发表时间：
2020-06-01
影响因子：
3.1
通讯作者：
Saphiannikova, Marina
中科院分区：
文献类型：
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作者：
Domurath, Jan;Ausias, Gilles;Saphiannikova, Marina
用玻璃纤维和碳纤维等棒状颗粒填充的聚合物熔体具有很高的实际意义。在这里，我们数值研究的性质，幂律流体充满刚性杆的不同的纵横比。为此，我们计算横向各向同性流体（TIF）方程的流变系数，并将我们的结果与分析模型进行比较，特别是与Souloumiac和Vincent（1998）的模型。在这里，我们发现，该模型预测的非线性制度的额外的取向依赖性太强，高估了我们的数值结果。TIF方程中的流变系数A取决于幂律模型的变薄指数，并随着非线性的增加而强烈减小。在牛顿情况下，我们发现Batchelor（1970，1971）大大低估了我们的数值结果。比较我们目前的数据与以前的结果为球体，我们发现，有没有这些颗粒在大的纵横比的流变系数之间的相似性。我们进一步分析了粒子的角速度和平移速度。我们发现，有牛顿和幂律矩阵流体之间的角速度可以忽略不计的差异，特别是对于大的纵横比。牛顿流体和幂律流体的平移速度完全相同。
Polymer melts filled with rod-like particles like glass and carbon fibers have high practical importance. Here we numerically investigate the properties of power-law fluids filled with rigid rods of different aspect ratios. For that we compute the rheological coefficients of the transversely isotropic fluid (TIF) equation and compare our results with analytical models, specifically with the model of Souloumiac and Vincent (1998). Here we found, that the additional orientation dependence predicted by the model for the nonlinear regime is too strong and overpredicts our numerical results. The rheological coefficient A in the TIF equation depends on the thinning exponent of the power-law model and decreases strongly with increasing nonlinearity. In the Newtonian case we found that Batchelor (1970, 1971) considerably underpredicts our numerical results. Comparing our current data with previous results for spheroids we found, that there is no similarity between the rheological coefficients for these particles at large aspect ratios. We further analyze the angular and translational velocities of the particles. We found that there are negligible differences in the angular velocities between the Newtonian and power-law matrix fluids, especially for large aspect ratios. The translational velocities are exactly the same for the Newtonian and power-law fluids.