On helical flows of polymer fluids

Isothermal and non-isothermal steady helical flows are theoretically invest igated under the assumption that the flow is fully developed in both the th ermal and hydrodynamic senses. It is well known that the basic gross charac teristics of steady isothermal helical flows of non-Newtonian liquids can b e found relatively easily if the flow curve (or non-Newtonian viscosity) in simple shearing is known. Nevertheless, evaluation of more detailed viscoe lastic properties in this type of flow is also sometimes desirable. These p roperties are shown to be exactly determined in both the isothermal and non -isothermal cases as soon as a nonlinear viscoelatic constitutive equation is specified. Shear thinning due to fluid rotation and strong temperature d ependence of Newtonian viscosity highly increase dissipative heat. This can produce significant non-isothermal effects in intense helical flows, even when the wall temperature is kept uniform and constant. It is shown that th e energy consumption in isothermal and non-isothermal helical flows is alwa ys higher than in respective annular flows with the same flow rate. Compari sons between our calculations and available experimental data are also disc ussed.