Nonlinear dynamics of nonisothermal viscoelastic entry flows

Nonlinear dynamics of non-isothermal viscoelastic flow in an axisymmetric s udden contraction geometry are brought out for a highly elastic polyisobuty lene (PIB) based polymer solution. The nonlinear effects present in such fl ows are due to the elastic nature of the polymeric fluid and the stratifica tion in the material properties created by the temperature gradient in the flow system. It is shown that these nonlinear effects have profound consequ ences for the onset, development, and structure of flows in nonisothermal v iscoelastic entry flows. Time temperature shifts that are traditionally use d to model temperature dependent material functions do not completely accou nt for the thermal effects observed here implying a need for the use of non isothermal constitutive equations derived from first principles using kinet ic theory.