Numerical study of 2D axisymmetric wavy-walled turbulent pipe flow and heat transfer with Al2O3-water nanofluid

A numerical study has been performed to investigate turbulent forced convective flow of Al2O3-water nanofluid inside a wavy-walled pipe subjected to uniform wall heat flux. The two-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations along with Shear Stress Transport (SST) turbulent model and Reynolds-Averaged energy equation in cylindrical coordinates are solved using finite element method. Numerical simulation is performed for either pure water or Al2O3-water nanofluid with constant solid volume fraction of φ = 2%, while the Kármán number is fixed at Reτ = 314. The implementation of wavy-walled surface over smooth-walled pipe can be considered as regular roughness, which ensures increased turbulence, whereas nanoparticles within base fluid improve thermal performance during turbulent transport mechanism. Therefore, their influences on mean velocity, mean temperature, Reynolds shear stress, radial heat flux, average Nusselt number and skin friction co-efficient are observed systematically. The results show that both the waviness of the pipe and the use of nanofluid potentially increase thermal performance for turbulent flow inside a heated pipe.