On a Scenario of Transition to Turbulence for a Polymer Fluid Flow in a Circular Pipe

Equations describing nonstationary and stationary flows of an incompressible polymer fluid through a pipe are derived based on the rheological mesoscopic Pokrovskii–Vinogradov model. Their exact stationary solutions are obtained and conditions providing their existence are outlined. Numerical simulation of the stabilization of a nonstationary flow is carried out and the restrictions on the values of parameters that ensure stabilization are computed. In a number of cases these restrictions coincide with the conditions of the existence of stationary solutions. The obtained results enable us to describe constructively the process of destruction of laminar Poiseuille-type flows, which usually initiates the onset of turbulence. The key role in mechanics of this process is played by the size and orientation of macromolecules of the polymer fluid. The mathematical description of the process uses essentially the solutions’ singular points.