ABSTRACT
The thermoviscoelastic fluids or polymeric fluids are both viscous and elastic. Such fluids consist of a solvent and a polymer. The solvent is generally a dilute solution that may be primarily viewed as Newtonian fluid. Its composition is due to short chain molecules. The polymer on the other hand consists of long chain molecules. It has its own viscosity in addition to elasticity. In thermoviscoelastic fluids, the elastic effects are primarily due to the polymer. When a polymeric fluid is subjected to a disturbance, the motion of the polymer molecules is complex (Brownian motion [83,84]). The polymeric fluids can be classified in two broad categories: dilute polymeric fluids and dense polymeric fluids or polymer melts. Compressibility in polymeric fluids is only important at very high pressures. Generally, polymeric fluids are treated as incompressible, hence it is appropriate to say polymeric liquids. Dilute polymeric fluids are primarily much like Newtonian fluids but with some elastic effects, i.e. the behavior is dominated by viscous effects. In such fluids the solvent viscosity is dominant, i.e. much higher than the polymer viscosity. Polymer melts, on the other hand, are dense polymeric fluids whose behavior is dominated by elastic effects. In such fluids the polymer viscosity is much higher than the solvent viscosity. Polymeric fluids are of significant industrial importance.
