Análise teórico-numérica de modelo constitutivo para fluidos tixotrópicos

Abstract

The thixotropic substances can be found in different industrial sectors, as the chemichal, food, manufacture and oil ones. The rheological behavior of such substances has a structure level time dependence. Generally, the constitute models for these substances are consisted of a two equations coupled system: the constitutive equation (based on viscoelastic models) and the rate equation (an equation that describes the microstructural features of the material). The shear modulus and the viscosity coefficient structural dependence are not formally considered in the dynamichal principle that origins the constitutive equation in other works. Therefore, it aims to analyse a new constitutive model presented at the literature, in which such inconsistencies do not occur. The constitutive equation is based on a modified Jeffreys model and the rate equation is grounded on the Smoluchowski coagulation theory. The model is analysed under a theoretical point of view, verifying some features assigned to the thixotropic materials. Numerical simulations and curve fitting of rheological tests are made, using a Matlab code, to validate the model.