| Abstract: | In the practical transporting of anomalous oils in pipelines and in the chemical industry it is necessary to take into account simultaneously various rheological effects inherent in liquids containing high molecular components in their composition. These effects are manifested in non-linearity of the effective viscosity, the appearance of normal stresses in shear flows (Weissenberg effect), and viscoelastic and thixotropic relaxation of stresses. There are models that describe various manifestations of such rheology 1, 2]. There are also models of a complex nature 3, 4], but these require experimental determination of various functions. The present paper presents a phenomenological tensor determining relation that reflects all the listed rheological anomalies observed in oils, solutions, and melts of polymers. It can be characterized as a model of a viscoelastic medium with two-step thixotropic relaxation. Heuristic arguments are presented that lead to this model, the results are given of calculation of the flow in a rotational viscosimeter of cylinder-cylinder type, the manifestation of the Weissenberg effect in the case of slow rotation of the drum of the viscosimeter is discussed, and experimental steady rheological curves are compared with theoretical curves.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 21–26, May–June, 1984. |
