The Rheological Responses of Dilute Polymers and the Analysis of their Flow Inside and Outside Channels

The behaviour of Oldroyd and Walters-Pre dries on modified models is analysed. To provide the siutable description for shearing and elongational flows it is convinient to use viscosity, relaxation time and retardation time that depend on the second and third invariants of the rate of deformation tensor. The introduction of the third invariant of the rate of deformation tensor in rheological equations is substantiated.