INFLUENCE OF TEMPERATURE AND PRESSURE ON VISCOELASTIC FLUID FLOW IN A PLANE CHANNEL

The hydrodynamics of a steady-state nonisothermal fl ow of a viscoelastic polymer medium in a plane channel and heat transfer in it under boundary conditions of the fi rst kind have been investigated. Fluid fl ow with a low Reynolds number and a high Péclet number was investigated, which made it possible to neglect the gravity and inertial forces, as well as the longitudinal thermal conductivity of the medium. From the rheological viewpoint, the polymer melt represents a viscoelastic fl uid; therefore the Phan-Thien–Tanner fl uid model was used as a rheological model of the fl uid, with viscosity depending on temperature and pressure. A high-viscosity medium was considered; therefore a dissipation term was included into the equation of the energy of its fl ow. With the use of the indicated rheological model the velocity profi le of fl uid fl ow was obtained in an explicit form from the equation of fl uid motion. It has been established that the dependence of the fl uid viscosity on temperature and pressure exerts a noticeable infl uence on the distribution of the Nusselt number and of bulk temperature of the fl uid along the channel length. It is shown that account for the temperature dependence of fl uid viscosity leads to a decrease in the role of energy dissipation of its fl ow in the process of fl ow heating and that, conversely, the dependence of the fl uid viscosity on pressure considerably enhances the dissipation effect. The problem has been solved numerically by the method of fi nite differences.
   
Author:  A. V. Baranov
Keywords:  viscoelastic fl uid, heat exchange, nonisothermal fl ow, dissipation
Page:  1296