Numerical Prediction for Thermal Oldroyd-B and Phan-Thien Fluids: Axisymmetric Contraction Flows

Abstract

  This article aims to study the numerical predictions of viscoelastic fluid behavior during flow in a 4:1:4 acute-angled contraction-expansion geometry under thermal boundary conditions (heating). The work studies non-Newtonian fluid flow response, in which viscoelasticity is introduced through two models, the constant viscosity Oldroyd-B model and shear-thinning exponential Phan-Thien Tanner (EPTT). The highly efficient, time-gradual pressure correction algorithm, Taylor Galerkin/ Pressure Correction finite element method, which is applied for the first time to this type of contraction-expansion problem, was implemented. The results showed the significant effect of varying the polymer solvent viscosity (β) ratio on the flow behavior and response of the Oldroyd B and EPTT velocity and pressure fields. The effect of temperature variables such as the Prandtl number (Pr) on thermal diffusion within the channel was also tracked. Our experimental observations reveal a marked superiority of the EPTT model in representing the flow problems of viscoelastic fluids compared to Oldroyd B fluids, and we will explain the reasons for this in this study. The results obtained indicate excellent agreement and accuracy.