Department of Mathematics and Statistics, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus.
J Chem Phys. 2018 Dec 28;149(24):244902. doi: 10.1063/1.5049397.
We propose a new description of elasto-viscoplastic fluids by relating the notion of thixotropy directly to internal viscoelasticity and network structures through a general, thermodynamically consistent approach. By means of non-equilibrium thermodynamics, a thermodynamically admissible elasto-viscoplastic model is derived which introduces self-consistently and effortlessly thixotropic effects and reproduces at both low and high shear rates experimental data usually fitted with empirical constitutive equations, such as the Bingham and Herschel-Bulkley models. The predictions of the new model are in very good agreement with available steady-state shear rheological data for soft colloidal pastes and blood, i.e., systems exhibiting a yield stress, and with time-dependent rheological data for blood, i.e., during a triangular time-dependent change in the shear rate, exhibiting a hysteresis. The proposed approach is expected to provide the means to improve our understanding of thixotropic fluids.
我们通过一种通用的、热力学一致的方法，将触变性的概念与内部粘弹性和网络结构直接联系起来，提出了一种新的弹粘塑性流体描述。通过非平衡热力学，推导出一个热力学允许的弹粘塑性模型，该模型自洽地引入了触变效应，并在低剪切率和高剪切率下重现了通常用经验本构方程（如宾汉和赫谢尔-布尔克利模型）拟合的实验数据。该新模型的预测与软胶体糊和血液（即具有屈服应力的系统）的稳态剪切流变数据以及血液的时变流变数据（即在剪切率的三角形时变过程中表现出滞后现象）非常吻合。预计该方法将为我们深入了解触变流体提供手段。
