论文标题
密度纤维悬浮液粘度的组成型模型
A constitutive model for viscosity of dense fiber suspension
论文作者
论文摘要
我们提出了一个本构模型，以预测纤维悬浮液的粘度，该模型以各种体积分数，纵横比和剪切应力/速率/速率/速率/速率/速率进行剪切稀疏。我们使用直接数值模拟的数据来校准模型，并通过预测文献中的实验测量来证明准确性。我们使用摩擦系数随着纤维之间的正常载荷而降低，以定量重现纤维悬浮液中的实验观察到的剪切稀疏。在该模型中，有效的正常接触力与散装剪切应力直接成正比，决定了有效的摩擦系数。剪切应力的增加可降低悬浮液中的有效摩擦系数。结果，堵塞的体积分数随着剪切应力而增加，从而导致悬浮粘度的剪切变薄。此外，我们扩展了模型，以量化悬浮液中纤维体积分数和宽高比的影响。我们使用来自速率控制的剪切流的数值模拟数据来校准该模型。校准后，我们表明该模型可用于预测不同体积分数，剪切应力和纵横比的相对粘度。模型预测与文献的可用实验测量非常吻合。这项研究的发现有可能用于调整纤维尺寸和体积分数，以设计各种应用中的悬架流变学。
We propose a constitutive model to predict the viscosity of fiber suspensions, which undergoes shear thinning, at various volume fractions, aspect ratios, and shear stresses/rates. We calibrate the model using the data from direct numerical simulation and prove the accuracy by predicting experimental measurements from the literature. We use a friction coefficient decreasing with the normal load between the fibers to quantitatively reproduce the experimentally observed shear thinning in fiber suspensions. In this model, the effective normal contact force, which is directly proportional to the bulk shear stress, determines the effective friction coefficient. A rise in the shear stress reduces the effective friction coefficient in the suspension. As a result, the jamming volume fraction increases with the shear stress, resulting in a shear thinning in the suspension viscosity. Moreover, we extend the model to quantify the effects of fiber volume fraction and aspect ratio in the suspension. We calibrate this model using the data from numerical simulations for the rate-controlled shear flow. Once calibrated, we show that the model can be used to predict the relative viscosity for different volume fractions, shear stresses, and aspect ratios. The model predictions are in excellent agreement with the available experimental measurements from the literature. The findings of this study can potentially be used to tune the fiber size and volume fraction for designing the suspension rheology in various applications.
