2017 Volume 12 Issue 1 Pages JFST0004
Thixotropy is a common behavior of soft matters widely used in various industries. Numerous models, both empirical and theoretical, have been proposed for different soft matters. In this paper the Maxwell viscoelastic model has been modified by decoupling the second order tensor type equation into vector type equations, without introducing new material parameters or assuming the dependence of the viscosity and/or elasticity on time and/or shear rate. The proposed Maxwell model is known as the vector type Maxwell model while the original one as the second order tensor type Maxwell model. The vector type Maxwell model was applied to both the stationary and the single step shear rate shear flow and the numeric results were compared with the experiments in the literature. It is found that the vector type Maxwell model predicted better both the shear and the normal stresses in the stationary shear flow than the second order tensor type Maxwell model, and the vector type Maxwell fluids may show thixotropic behavior in the single step shear rate flow as observed in experiments.