Forced convection heat transfer of Giesekus fluid with wall slip above the critical shear stress in pipes

• Published in: The International journal of heat and fluid flow 2018-06, Vol.71, p.442-450
• Main Authors: Mohseni, Mehdi Moayed, Tissot, Gilles, Badawi, Michael
• Format: Article
• Language: English
• Subjects: Cooling and heating cases; Engineering Sciences; Fluid elasticity; Giesekus constitutive equation; Nusselt number; Reactive fluid environment; Slip effect; Viscous dissipation
• ISSN: 0142-727X; 1879-2278
• DOI: 10.1016/j.ijheatfluidflow.2018.05.005

•Increasing slip effect increase Nusselt number in Br > 0.•Nusselt number decrease by increasing Brinkman number in Br > 0.•For the cooling case fluid starts to warm up in Br > Br1.•Nusselt curve show a singularity in Br2.•Br1 and Br2 increase by Increasing slip effect. Forced convective heat transfer in pipes is investigated for viscoelastic fluids obeying the Giesekus constitutive equation including effect of slip condition by an approximated analytical method. The slip equation at wall is considered as a nonlinear Navier model with non-zero slip critical shear stress. The problem under consideration is steady, laminar and fully developed. Thermal boundary conditions are assumed peripherally and axially constant heat flux at wall. The fluid heating and cooling cases are considered for analysis. Dimensionless temperature profiles and Nusselt number are obtained by solving governing equations and the effects of slip parameters, viscous dissipation and fluid elasticity are discussed. Results show that Nusselt number increases by increasing slip effect but decreases by increasing Brinkman number for the case of fluid heating. However, for the cooling case, the heat generated by viscous dissipation can overcome the effect of wall cooling at first critical Brinkman number and fluid starts to warm up. Also the Nusselt curve shows a singularity in a second critical Brinkman number.