This study numerically investigates forced convection heat transfer of a viscoelastic fluid around a cylinder in steady and unsteady regimes in presence of viscous dissipation, using finite volume method. The Phan-Thien–Tanner (PTT) model describes the viscoelastic behavior of the viscoelastic fluid. To avoid divergence and stabilize the numerical process in high elastic cases, the log-conformation approach proposed by previous researchers is used. The Nusselt number (Nu) was monotonically increased with increasing elasticity number (El), retardation ratio, Prandtl number (Pr), and Brinkman number (Br) in a wide range. Both drag reduction and drag enhancement are seen in the numerical results. The effect of consideration of temperature-dependent properties on the results was investigated. Results show that the elastic forces made the vortices behind the cylinder smaller, and stronger. In addition, the elasticity delays the three-dimensional instabilities in cylinder axis direction. Finally, the effects of El,model parameters, Pr, and Br on the distribution of stress components, velocity and temperature distributions, Nu, shedding frequency, and drag and lift coefficients, are investigated separately and physical discussion is presented. Key Words: forced-convection, heat transfer, viscoelastic fluid, non-Newtonian, PTT, cylinder, numerical simulation
