Development length of fluids modelled by the gPTT constitutive differential equation

In this work, we present a numerical study on the development length (the length from the channel inlet required for the velocity to reach 99% of its fully-developed value) of a pressure-driven viscoelastic fluid flow (between parallel plates) modelled by the generalised Phan–Thien and Tanner (gPTT) constitutive equation. The governing equations are solved using the finite-difference method, and, a thorough analysis on the effect of the model parameters α and β is presented. The numerical results showed that in the creeping flow limit (Re=0), the development length for the velocity exhibits a non-monotonic behaviour. The development length increases with Wi. For low values of Wi, the highest value of the development length is obtained for α=β=0.5; for high values of Wi, the highest value of the development length is obtained for α=β=1.5. This work also considers the influence of the elasticity number.This research was funded by FCT—Fundação para a Ciência e a Tecnologia, through projects UIDB/00532/2020 and UIDP/00532/2020 of CEFT (Centro de Estudos de Fenómenos de Transporte), and through PTDC/EMS-ENE/3362/2014 and POCI-01-0145-FEDER-016665—funded by FEDER funds through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI) and by national funds through FCT. It was also funded by FCT through the CMAT projects UIDB/00013/2020 and UIDP/00013/2020 (CMAT—Centro de Matemática e Aplicações); and was funded by Fapesp-Fundação de Amparo à Pesquisa do Estado de São Paulo, Fapesp-2017/21105-6 and Petrobrás (Project 0050.0075367.12.9). Research was carried out using the computational resources of the Center for Mathematical Sciences Applied to Industry (CeMEAI), funded by FAPESP grant 2013/07375-0